A literature review of cancer diagnostic tests and treatments in adults with intellectual disability.

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Learn more: PMC Disclaimer | PMC Copyright Notice HRB Open Res . 2026 Apr 15;8:66. Originally published 2025 Jun 13. [Version 3] doi: 10.12688/hrbopenres.14164.3 Other versions PMC13000398.1; 2025 Jun 13 PMC13000398.2; 2026 Feb 24 PMC13000398.3; 2026 Apr 15 Search in PMC Search in PubMed View in NLM Catalog Add to search A literature review of cancer diagnostic tests and treatments in adults with intellectual disability Kennedy Smihula Kennedy Smihula 1 College of Nursing, The Pennsylvania State University, University Park, Pennsylvania, USA Data Curation, Formal Analysis, Investigation, Methodology, Validation, Visualization, Writing – Original Draft Preparation, Writing – Review & Editing Find articles by Kennedy Smihula 1 , Mikayla Danon Mikayla Danon 1 College of Nursing, The Pennsylvania State University, University Park, Pennsylvania, USA Data Curation, Formal Analysis, Investigation, Methodology, Validation, Visualization, Writing – Original Draft Preparation, Writing – Review & Editing Find articles by Mikayla Danon 1 , Shauna Walsh Shauna Walsh 2 Trinity College Dublin School of Nursing and Midwifery, Dublin, Leinster, Ireland Formal Analysis, Investigation, Methodology, Project Administration, Supervision, Writing – Review & Editing Find articles by Shauna Walsh 2 , Martin McMahon Martin McMahon 2 Trinity College Dublin School of Nursing and Midwifery, Dublin, Leinster, Ireland Conceptualization, Funding Acquisition, Methodology, Project Administration, Resources, Supervision, Validation, Visualization, Writing – Review & Editing Find articles by Martin McMahon 2 , Louise Lynch Louise Lynch 2 Trinity College Dublin School of Nursing and Midwifery, Dublin, Leinster, Ireland Conceptualization, Data Curation, Formal Analysis, Investigation, Methodology, Project Administration, Resources, Supervision, Validation, Visualization, Writing – Original Draft Preparation, Writing – Review & Editing Find articles by Louise Lynch 2, a Author information Article notes Copyright and License information 1 College of Nursing, The Pennsylvania State University, University Park, Pennsylvania, USA 2 Trinity College Dublin School of Nursing and Midwifery, Dublin, Leinster, Ireland a Email: [email protected] No competing interests were disclosed. Roles Kennedy Smihula : Data Curation, Formal Analysis, Investigation, Methodology, Validation, Visualization, Writing – Original Draft Preparation, Writing – Review & Editing Mikayla Danon : Data Curation, Formal Analysis, Investigation, Methodology, Validation, Visualization, Writing – Original Draft Preparation, Writing – Review & Editing Shauna Walsh : Formal Analysis, Investigation, Methodology, Project Administration, Supervision, Writing – Review & Editing Martin McMahon : Conceptualization, Funding Acquisition, Methodology, Project Administration, Resources, Supervision, Validation, Visualization, Writing – Review & Editing Louise Lynch : Conceptualization, Data Curation, Formal Analysis, Investigation, Methodology, Project Administration, Resources, Supervision, Validation, Visualization, Writing – Original Draft Preparation, Writing – Review & Editing Accepted 2026 Apr 1; Collection date 2025. Copyright: © 2026 Smihula K et al. This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. PMC Copyright notice PMCID: PMC13000398  PMID: 41868999 Version Changes Revised. Amendments from Version 2 - Diagnotics tools has been replaced with diagnostic procedures. - Cancer patients with intellectual disability has been replaced with individuals with intenllectaul disability. - The PICOS framework has been replaced with PICoS. - The PRISMA diagram has been updated to refelct correct overall numbers. - More deatils have been added on data extraction, screening and thematic analysis. - Sentence added to conclusion on policy and practice. Abstract Background Adults with intellectual disabilities have significantly lower rates of routine cancer screening and cancer is often diagnosed at more advanced stages. Some studies highlight gaps that exist in national screening programmes for cancers such as breast, cervical and colorectal. Evidence in the intellectual disability population points towards factors such as limited screening education, distrust in healthcare providers, and challenges in providing consent, leading to limited uptake of screening programmes. While there are many contributing factors to these inequalities, changes in individuals' health status may go unrecognised for longer because of their intellectual disability. The aim of this literature review is to explore cancer diagnostic approaches and treatment options for adults with intellectual disability and examine barriers to accessing diagnostic procedures and treatments. Methods Five electronic databases were systematically searched: Cinahl Ultimate, Medline, PsycINFO, PubMed, and Web of Science. Thematic analysis was completed using the Braun and Clark Six Step process. Results Four main themes emerged from 28 included studies: Prevention, education, adaptation, and ethical practice. Prevention encompassed individuals receiving regular screening and barriers that prevented access. Educational tools that explained the importance of screening reduced feelings of stress and anxiety. Case studies illustrated how specific treatment plans were adapted for patients with intellectual disability. Autonomy and honesty were themes throughout many studies, in terms of treatment, education, and diagnostics. It was determined that patients should be involved in decision making and be aware of their cancer diagnosis unless there are contra-indications. Conclusion Adults with intellectual disability face considerable barriers when accessing cancer diagnosis and treatment. Barriers, including living conditions, communication difficulties and age, contributed to later cancer diagnosis and worse outcomes, compared to the general population. The successful use of education and tailored treatments were enabling factors. Keywords: Autonomy, Cancer, Intellectual Disability, Screening, Treatments Introduction In recent years improvements in cancer care and survival in the general population have been observed Loud & Murphy (2017) . Studies have emphasised the importance of regular screening and the role that this plays in the early detection of cancer ( Ding et al. , 2022 ; Miller, 2013 ; Whitaker, 2020 ). Advancements in treatment options, as well as secondary prevention and early detection, are leading to better outcomes and decreased cancer mortality rates in the general population ( Ding et al. , 2022 ; Gini et al. , 2020 ; Jemal et al. , 2010 ). Despite these recent developments in treatment, and the implementation of national cancer screening programmes, large gaps exist in diagnostic and treatment options between people with intellectual disability and the general population ( Cuypers et al. , 2024 ; Mahar et al. , 2024 ). Adults with intellectual disability have significantly lower rates of routine cancer screening and cancer is often diagnosed at more advanced stages ( Horsbøl et al. , 2023 ; Kiani et al. , 2014 ). Some studies specifically highlight gaps that exist in national screening programmes for cancers such as breast, cervical and colorectal ( Satgé et al. , 2023 ; Sullivan et al. , 2003 ; Swaine et al. , 2014 ). Evidence in the intellectual disability population points towards factors such as limited screening education, distrust in healthcare providers, and challenges in providing consent, leading to limited uptake of available screening programmes and there appear to be misassumptions by health professionals and carers that women with intellectual disability do not require cervical screening due to being sexually inactive ( Power et al. , 2024 ; Swaine et al. , 2014 ; Weise et al. , 2024 ; Xu et al. , 2017 ). While there are many contributing factors to these inequalities, changes in individuals' health status may go unrecognised for significantly longer because of their intellectual disability ( Kiani et al. , 2014 ). In some cases, symptoms suggestive of cancer and cancer itself go undetected, and cancers are identified at a late stage or as a cause of death in individuals with intellectual disability ( Heslop et al. , 2022 ; Mahar et al. , 2024 ). Communicating symptoms of cancer may be difficult for individuals with an intellectual disability, and those around them may not notice signs of illness, or attribute changes in behaviour to their intellectual disability, both reasons which may contribute to a late-stage cancer diagnosis ( Satgé et al. , 2014 ). Ultimately this phenomenon, known as diagnostic overshadowing, may contribute to a decreased quality of life and the unnecessary progression of cancer, resulting in premature mortality ( Mason & Scior, 2004 ; McMahon et al. , 2024 ). Although cancer is being diagnosed at more advanced stages in adults with intellectual disability, the evidence does not show that diagnosis occurs later in life ( Mahar et al. , 2024 ; Satgé et al. , 2014 ). In a study conducted by Satgé and colleagues, the age at which individuals with intellectual disability were being diagnosed with cancer was younger than the recommended screening age for the general population with Heslop et al . (2022) and Mahar et al. (2024) reporting similar findings in England and Canada respectively. This may be an indication that adults with intellectual disability are developing cancer earlier in adulthood, and screening protocols may need to be tailored to this. Recent evidence has shown that individuals with intellectual disability were 1.6 times more likely to be diagnosed with Stage IV breast cancer and 1.44 times more likely to be diagnosed with Stage IV colorectal cancer ( Mahar et al. , 2024 ). While the reasons why they are developing late-stage cancer at earlier ages have not yet been established, studies suggest that lowering screening ages for people with intellectual disability could be beneficial for earlier diagnosis ( Heslop et al. , 2022 ; Mahar et al. , 2024 ; Satgé et al. , 2014 ). The prognosis for cancer patients is dependent on the cancer stage at diagnosis, so a later diagnosis in patients with intellectual disability could be a key factor accounting for differences in mortality rates ( Mahar et al. , 2024 ; McMahon et al. , 2024 ; Satgé et al. , 2014 ). There is limited research that focuses on treatment options for individuals with intellectual disability diagnosed with cancer. Much of the published evidence are case studies based on one individual's cancer experience with no synthesis of the published evidence available ( Brown, 2011 ; Enomoto et al. , 2015 ). In terms of diagnostic tools, while individuals with intellectual disability may utilise the same tools as the general population, tools such as mammography, Papanicolaou tests (pap smears), and testicular examinations, remain under-utilised by the intellectual disability population ( Satgé et al. , 2023 ). The existing gaps in cancer diagnosis may be from patients not receiving regular screening ( Chan et al. , 2022 ; Sullivan et al. , 2003 ). Although the exploration of treatments in case studies are specific to individual patients, these treatments may set a precedent that tailored treatment plans are required for the specific needs of this vulnerable population ( Brown, 2011 ; Delany et al. , 2023 ; Satgé et al. , 2014 ; Sleijfer et al. , 1996 ). Consequently, the aim of this literature review is to explore and synthesise information relating to cancer diagnostic approaches and treatment options for adults with intellectual disability and examine the barriers that prevent adults with intellectual disability from accessing both diagnostic tools and treatments. Methods A literature review guided by the PRISMA Extension for Scoping Review checklist was undertaken to understand the experiences of adults with intellectual disability undergoing cancer diagnostic tests and treatments. Literature reviews provide a broad, thorough critique and examination of all the evidence available on the topic and facilitate a descriptive analysis and meaningful synthesis of the current available research ( Colquhoun et al. , 2014 ). 1. Research question The PICoS (Population, Intervention, Context, Study Type) framework was used to frame the research question and search concepts for this review. The research question to be addressed is: ‘What are the barriers or enablers to accessing cancer diagnostics and treatment for adults with intellectual disability?’ This will be achieved through two objectives: • Explore and synthesise information relating to cancer diagnostic approaches and treatment options for adults with intellectual disability. • Examine barriers and enablers to accessing cancer diagnostic tools and treatments for adults with intellectual disability. 2. Eligibility criteria The eligibility criteria are summarised in Table 1 . Table 1. Literature review eligibility criteria. Include Exclude Population - Adults with all levels of intellectual disability - Down syndrome and other syndromes (if intellectual disability presence confirmed) - Children, teenagers under 18 years of age - Adults without intellectual disability Intervention/Exposure - Any diagnosis and treatment of cancer - Studies with no specified focus on diagnosis or treatment of cancer Context - Barriers and enablers influencing access to cancer diagnostic procedures and treatment - None Study Characteristics - Observational (retrospective and observational) - Qualitative - Cohort studies - Randomised control trials - Reviews - Editorials or opinion pieces - Book chapters Language - English - All non-English languages Open in a new tab 3. Search strategy Five electronic databases were systematically searched: Cinahl Ultimate, Medline, PsycINFO, PubMed, and Web of Science. To provide the most accurate search, search functionality and keywords were used and adjusted accordingly for each database. Keywords included “intellectual disability”, “treatment”, “diagnosis”, and “cancer”. Boolean operators were employed, including “and”, “or”, along with “not”. Table 2 shows an example of the MEDLINE search string. Finally, citations were searched in relevant reviews about cancer treatments and screening for adults with an intellectual disability. All articles were extracted to Covidence which was used as the screening tool. Table 2. An example of the MEDLINE search string. Concept Index Keywords Concept 1: Cancer (MH “Cancer”) (Cancer OR oncology OR neoplasm OR malignant OR malig*) Concept 2: Intellectual disability or learning disability (MH “Intellectual Disability+”) OR (MH “Learning Disabilities+”) ((intellectual AND disabilit* OR ‘mental retardation’/exp OR ‘mental retardation’ OR (mental AND (‘retardation’/exp OR retardation)) OR ‘learning’/ exp OR learning) AND disabilit* OR developmental) AND disabilit* OR ‘learning disabilities’/exp OR ‘learning disabilities’ OR ((‘learning’/exp OR learning) AND disabilities) Concept 3: Diagnosis (MH “Diagnosis”) (diagnos* OR screen* OR assess* OR evaluation OR detect* OR identif*) Concept 4: Treatment (MH “Therapeutics”) (treat* OR therap* OR intervention OR management OR care OR “therapeutic approach” OR “clinical management”) Open in a new tab 4. Screening process Figure 1 summarises the screening process in a PRISMA diagram. Two assessors [KS, MD] reviewed each of the articles. A third [LL or MMcM] adjudicated in cases of dispute. The initial search resulted in 10,534 publications with 3,991 duplicates removed. A title and abstract screening of 6,543 articles was completed. Then, 236 articles proceeded to full-text review. Finally, 23 articles were extracted, along with three articles from citation searching and two additional proposed articles, resulting in a total of 28 articles for inclusion in the literature review. Figure 1. PRISMA diagram. Open in a new tab 5. Data extraction Data was gathered from studies conducted worldwide from 1996 to 2024. The following information was extracted from each article: author, year, country, study aim, study design, sample size, age, gender, results and theme, and summarised in an excel spreadsheet, see Table 2 . All information was not available for each article. 6. Thematic analysis A qualitative synthesis and thematic analysis was completed independently by two researchers (KS, MD) on the extracted articles using the Braun and Clark Six Step process, see Table 3 ( Braun & Clarke, 2006 ). After each step the researchers reconvened and compared results. Any differences were discussed with the other researchers (LL, McM) until resolution was reached. Initially the researchers familiarised themselves with each article’s content by reading multiple times and making notes on each, to fully immerse themselves in the data. As initial patterns emerged, colour-coding was used to group similar codes together. Broad themes emerged as a result of this grouping. These broad themes were then refined further, analysing the codes that were contained in each theme until four broad themes remained. Some articles were grouped into multiple themes as they covered multiple topics. Table 3. Six step thematic analysis process. Step number Process Explanation 1 Data familiarisation Complete data immersion 2 Generate initial codes Topics, patterns of data 3 Search for themes Broader theme identification 4 Review of themes Theme refinement 5 Define and name themes Categorise. Include sub-themes if required 6 Produce report Complete write-up Open in a new tab ( Braun & Clarke, 2006 ) Results A total of 28 articles were included in the final review. After completing the Braun and Clark thematic analysis, the four overriding themes emerged i.e. Prevention, Education, Adaptation and Ethical practice. Some overlap was observed in articles that covered multiple themes ( Armin et al. , 2022 ; Brown, 2011 ; Flynn et al. , 2016 ; Sleijfer et al. , 1996 ; Sullivan et al. , 2003 ). The number of people with intellectual disability represented in this review was 119,909. Studies were representative of a worldwide population; USA (n=7), UK (n=6), Canada (n=5), France, Australia and Japan (n=2), and Sweden, Denmark, Taiwan and The Netherlands (n=1). Overall, 16 articles investigated preventative measures of cancer screening, seven articles discussed education on cancer and screening for people with intellectual disability, seven articles reviewed cancer treatment options for individuals with intellectual disability, and three articles discussed patient autonomy, which was covered by ethical practices, see Table 4a and Table 4 in extended data. A summary of each theme’s results is provided. Screening was addressed in prevention and education. Treatments were covered by adaptation and ethical practice. Table 4a. Article extraction summary. Author, year Country Aim Design Age % Male No of participants Results Theme Armin et al. , 2022 USA Identify barriers to cancer screenings in native American patients with intellectual disability Semi-structured interviews 18–44 7% n=48 Individual, interpersonal, and community/institutional barriers to screenings due to social inequities. They were then utilised in creating a cancer screening education program. Prevention, Education Bates and Triantafyllopoulou, 2019 UK Determine barriers and mental capacity impact on breast cancer screenings for women with intellectual disabilities Cross-sectional survey 50–70 0% n=131 Barriers to screening include poor mobility and behavioural difficulties. Also, women who lacked mental capacity were less likely to engage in the screenings. Prevention Brown et al. , 2016 Canada To compare cervical cancer screening rates in women with and without intellectual disability who had a pregnancy Retrospective cohort 29–64 0% n=5,033 (with intellectual disability), n=527,437 (without intellectual disability) Women with intellectual disability were less likely than women without intellectual disability to be screened, after controlling for health and social factors. Prevention Cobigo et al. , 2013 Canada To estimate rates of cervical & breast cancer screening among eligible women with intellectual disability & compare to women without intellectual disability; To examine if any observed differences between the groups persist after certain factors are accounted for Cross-sectional using health administrative data and registries 20–69 0% n=17,777 with intellectual disability, n=1,440,962 without intellectual disability Women with intellectual disability are almost twice less likely to be screened for cervical cancer and 1.5 less likely to receive mammograms than women without intellectual disability. Prevention Flynn et al. , 2016 UK Explore the experiences of people who have an intellectual disability and their diagnoses and treatment of cancer Interviews conducted and analysed using Grounded theory 34–77 N/A Patients with Intellectual disability & cancer n=6, Family & healthcare professionals n=12 People with intellectual disability were often excluded from decisions in their cancer care and treatment. However, when they were included, there were positive outcomes with meaningful engagement of their care. Therefore, more methods put into play in aiding patients with intellectual disability to understand their diagnoses Prevention, Ethical practice Heslop et al. , 2022 England Expand the current understanding of cancer and screenings in adults with intellectual disabilities Population based study 20+ n/a n=1096 In individuals with intellectual disabilities who were deceased, cancers were presented in emergency situations, 45% being stage IV cancers at diagnosis. Of these cancer related deaths, 36% were digestive system cancers and 48% of these were colon cancers. 43% of the patients who died of colon cancer were below the screening age recommended for the general population. Prevention Horsbøl et al. , 2023 Denmark Compare breast cancer screening Cohort study 50–69 0% Patients with intellectual disability n=5595, Patients without intellectual disability n=49,423 25% of patients with intellectual disabilities were fully screened compared to 62% of patients who did not have intellectual disabilities. Additionally, 45% of patients with intellectual disabilities had never been screened compared to 13% in the population that does not have intellectual disability. As patients' severity of intellectual disability increased their likelihood of screening decreased. Prevention Kiani et al. , 2014 UK Case of an individual with a profound Intellectual disability who developed a chest infection, and recurrent infections after that and was then diagnosed with cancer after death in the patients’ autopsy Case study 56 100% n=1 The patient's cancer symptoms had been attributed to his chest infections, and whether an early diagnosis could have altered the patient's outcome, the health care team should have further investigated these symptoms. Prevention Lai et al. , 2014 Taiwan Investigate the rate of uptake of mammography and pap smears in patients with intellectual disability. Then, determine external factors that may influence utilising these cancer screening methods. Population based study 50–69 0% n=4370 The mammography utilisation rate for women with intellectual disability was 4.32% compared to the general population of 12%. There were external factors also discovered that could lead to increased or decreased utilisation including marriage, education, and other preventive health use. Prevention Mahar et al. , 2024 Canada Determine the incidence and disparities between people with intellectual disabilities and their delayed diagnoses for breast, colorectal, and lung cancers Multiple population-based cross-sectional studies 49–80 Breast cancer- 0% Colorectal cancer- 54% Lung cancer- 50.3% Patients with intellectual disability & breast cancer n=83, Patients with breast cancer, n=10,610, Patients with intellectual disability & colorectal cancer n=84, Patients with colorectal cancer n=10,283, Patients with intellectual disability & lung cancer n=67, Patients with lung cancer n=11,400 Patients with intellectual disabilities were 1.6 times more likely to be diagnosed with breast cancer and 1.44 times more likely to be diagnosed with colorectal cancer at stage IV compared to patients without intellectual disability due to low screening rates and delayed diagnosis. Prevention Ouellette-Kuntz et al. , 2015b Canada Examine the participation of patients with intellectual disabilities in colorectal cancer screenings Routine-data-based study 50–64 53.9% with Intellectual disability, 49.4% without Patients with Intellectual disability n=15,791, Patients without n=791,792 In each age range for participants, the percentage of males with intellectual disabilities was at least 10.7% lower than their counterparts without intellectual disabilities. Prevention Ouellette-Kuntz et al. , 2015a Canada Compare the utilisation of secondary screenings and prevention in adults with and without intellectual disabilities Retrospective cohort study 18–64 19.9% with Intellectual disability, 20.5% without Patients with intellectual disabilities n= 66,484, Patients without intellectual disabilities n=2,760,670 26.4% of adults without intellectual and developmental disabilities had a regular health examination over the two-year period in comparison to the 22% of individuals with intellectual disabilities. The study found that adults with intellectual and developmental disabilities were less likely to undergo recommended screenings for breast, colorectal and cervical cancer. Prevention Satgé et al. , 2023 France Examine the colorectal screening rates for patients with intellectual disabilities and what stage these patients are being diagnosed with colorectal cancer. Then, compare these rates with the general population and determine any disparities if present Registry review 32–85 35.70% n=14 patients 64.3% of the time patients with intellectual disability are diagnosed with colorectal cancer at stage IV compared to the general population at 26%. Out of these patients 10 died soon after their diagnosis due to advanced tumour stages not allowing for treatments. It was discovered that people with intellectual disabilities do not participate in as many faecal occult blood tests which is a common screening for colorectal cancer and may be the reason they are receiving delayed diagnosis. Therefore, it is important to increase the number of screenings for this population. Prevention Satgé et al. , 2014 France Compares age of diagnosis, tumour size, Scarff-Bloom-Richardson grading, TTMN classification and AJCC stage in women with and without Intellectual disability Retrospective study 40–55 0% 484 total, n=11 with intellectual disabilities In women with intellectual disabilities, breast cancer was diagnosed at a mean age of 55.64 years while the mean age in women without intellectual disabilities was 62.35. The tumour size in women with intellectual disabilities was found to have a range of 1.5–8 cm which is greater than the control group. Prevention Sullivan et al. , 2003 Australia Compare the incidence of breast cancer and the uptake of mammography screening services by women with intellectual disabilities Audit based on Disability Services Commission database 25+ 0% n=2,370 34.7% of patients with intellectual disabilities utilised breast cancer screening methods such as mammograms compared to 54.6% in the general population. This proves the underutilisation of these services in this population. Prevention, Education Tuffrey-Wijne et al. , 2010 ) UK Explore how much people with intellectual disabilities are told and understand about their diagnosis of cancer Ethnographic study 36–66 53% n=13 11 out of 13 patients were told they had cancer, but most did not understand their diagnosis or prognosis and were kept apart from the decision-making process of their care and treatment. It was also determined that the worse the persons' intellectual disability was the lessened their probability of being told about their diagnosis and had a lower sense of understanding. Prevention, Ethical practice Armin et al. , 2023 USA An education programme for native American women with intellectual disability called "My Health, My Choice" in hopes of increasing screening uptake for this population Pre- and post-survey 18–44 0% n=12 The patients were able to undergo surgeries that are not normally applicable for this population. This shows that these types of treatments that normally are not options for this population can be accessible with minor modifications and lead to improved health outcomes Education Greenwood et al. , 2014 USA Evaluate acceptability, demand and limited efficacy of a health education DVD about mammography for women with Intellectual disability Feasibility study 37–82 0% n=27 The DVD was proven successful as the patients demonstrated increased knowledge of mammography screenings. All the participants except one rated highly the statement that they learned a lot from the DVD, which had a rating overall of 4.4 and all the participants except four requested to keep the DVD. Education Swaine et al. , 2014 USA Evaluate if the version Women Be Healthy 2 is effective in increasing the knowledge of women with Intellectual disability regarding breast & cervical screening Randomised control trial 36–37 0% n=198 Women with intellectual disabilities who underwent the Women Be Healthy 2 programme demonstrated an increased understanding of breast and cervical screenings in comparison to women with intellectual disabilities who did not undergo the programme. Education Wang et al. , 2015 USA To determine the validity of the Mammography Preparedness Measure Pilot testing of a measurement instrument, followed by assessing the test-retest reliability of the Mammography Preparedness Measure 37+ 0% n=48 The Mammography Preparedness Measurement was found to be a valid instrument for assessing the preparedness of women with intellectual disabilities to receive a mammogram. The tool was found to have a test-retest per cent agreement of 84%. Education Wilson et al. , 2018 UK To assess and compare the impacts that a leaflet informational packet and an educational programme utilising videos have on testicular health Participatory randomised parallel study of two educational interventions 16–34 100% n=192 One week after the intervention the educational programme group scored significantly higher in an assessment of their knowledge and skills of testicular health. However, in from week 1 to 6 months both the leaflet and educational programme groups demonstrated this increase in knowledge and skills. Additionally, there was a significant increase in self-efficacy in both groups where individuals felt confident enough to perform self-testicular exams. Education Brown, 2011 USA Patients with intellectual disability receiving allogeneic transplant and other aggressive cancer treatments without understanding their options Case-study audit n/a 100% n=1 The patient passed away within a year of the transplant and follow up treatment due to pneumonia and underwent visible suffering throughout Adaptation, Ethical practice Delany et al. , 2023 Australia Modified chemotherapy and communication methods to tailor patient needs & Intellectual disability Case-study audit 33 100% n=1 Patient made a complete recovery after chemotherapy with the help of collaboration and communication between clinical teams, family and carers throughout the treatment. Paper argues this should be the new standard for this population. Adaptation Enomoto et al. , 2015 Japan Case of oral cancer and the three rounds of modified and specialised chemotherapy they underwent using infusions to the femoral artery Case-study audit 32 100% n=1 The patient made a great recovery and has had no signs of recurrence. The paper explains further how much more successful treatments can be for this population with modifications to meet their needs. Adaptation Gandhidasan et al. , 2020 USA Outpatient anaesthesia facilitating delivery of stereotactic body radiation therapy in patients with severe cognitive impairments and inoperable lung cancer. Retrospective review 44–78 38% n=7 Outpatient anaesthesia was tolerated by the patients and the stereotactic body radiation therapy was able to be completed in patients with cognitive impairments. There was one stereotactic body radiation related toxicity that resulted in grade 5, however there were no other toxicities above grade three found. Adaptation Ishimaru et al. , 2022 Japan Investigate Tumour Screening, Incidence, and Treatment for Patients Intellectual Disabilities Chart review 27–67 50% n=12 The patients were able to undergo surgeries that are not normally applicable for this population. This shows that these types of treatments that normally are not options for this population can be accessible with minor modifications and lead to improved health outcomes Adaptation Segerlantz et al. , 2019 Sweden Comparison of prescription pain medications in cancer patients with intellectual disabilities, and cancer patients in the general population National registry cohort study 55 years + n/a n=555 patients with Intellectual disability, n=877 cancer patients from the general population Cancer patients with intellectual disabilities are less likely to be prescribed COX inhibitors, and weak opioids, but more likely to be prescribed paracetamol, and antidepressants than cancer patients in the general population. Adaptation, Ethical practice Sleijfer et al. , 1996 Netherlands Report on a patient who has down syndrome and a disseminated seminomatous tumour of the testis and what their treatment entailed Case study 30 100% n=1 Cisplatin-based regimens of chemotherapy are difficult for patients with intellectual disability to undergo though this patient had remarkable success with a carboplatin-containing chemotherapy, since it is available to be administered on an out-patient basis making it an improved alternative to the former. Adaptation, Ethical practice Open in a new tab (a) Prevention The importance of cancer screening as a preventative measure for people with intellectual disability due to noted higher risks of developing cancer and having difficulties with explaining their pain and symptoms, was discussed in 14 articles. Armin et al. (2022) found that social inequalities contributed as barriers to screening for adults with an intellectual disability while intellectual disability severity level was negatively associated with screening levels ( Horsbøl et al. , 2023 ). Additionally, this population were less likely to receive cancer screening in comparison to the general population due to unique barriers including living conditions, and distress and anxieties they experience may make them less likely to engage with screening ( Tuffrey-Wijne et al. , 2010 ). For example, Canadian women with intellectual disability are less likely to receive cervical screening than women without intellectual disability, in some cases almost twice less likely, even if they were confirmed to be sexually active, and 1.5 times less likely to receive mammograms ( Brown et al. , 2016 ; Cobigo, 2013 ). Similarly, a Taiwanese study reported that the breast cancer screening and cervical screening rates for women with intellectual disability was almost three times and six times less than women in the general population ( Yen et al. , 2014 ). In addition, women with intellectual disability are five times more likely to never be screened for cancer than the general population and a lower rate of mammograms is observed in women with intellectual disability ( Ishimaru et al. , 2022 ; Lai et al. , 2014 ). Similarly, men with intellectual disability had lower rates of cancer screening. A Canadian routine data-based study on colorectal cancer (n=807,583) reported that 18.3% of intellectual disability participants received a faecal occult blood test in the previous two years, while 32% were up to date with their colorectal screening, compared to the general population at 26.4% for screening in the last two years and 47.2% for being up to date with their screening ( Ouellette-Kuntz et al. , 2015a ). Furthermore, mobility, behavioural issues and a lack of mental capacity emerged as barriers for women with intellectual disability receiving cancer screening ( Bates & Triantafyllopoulou, 2019 ). Lower levels of cancer screening resulted in increased numbers of late-stage cancer diagnoses with higher levels of poor health outcomes ( Heslop et al. , 2022 ; Satgé et al. , 2014 ). A concern is that people with intellectual disability have presented with cancer at ages below those recommended for screening commencement for the general population ( Heslop et al. , 2022 ; Mahar et al. , 2024 ; Satgé et al. , 2023 ). (b) Education Education and information about cancer screening and treatments was explored in seven articles. Various screening educational tools were used, including the ‘Mammography Preparedness Measure’ which assessed women’s readiness for Mammograms and a testicular cancer education programme which resulted in improved self-efficacy among men with intellectual disability ( Wang et al. , 2015 ; Wilson et al. , 2018 ). An American ‘My Health My Choice’ program demonstrated that appropriate education and information resulted in treatment options being offered that would otherwise not be presented ( Armin et al. , 2023 ). The American ‘Women Be Healthy 2’ program and DVDs as educational tools were positively received by adults with an intellectual disability and demonstrated an increase in knowledge of screening ( Greenwood et al. , 2014 ; Swaine et al. , 2014 ). (c) Adaptation The modification of treatments to make them more amenable to individuals with intellectual disability was the third theme that emerged in this review. Specific cancer treatments for individuals with intellectual disability were detailed in seven articles. Adapted chemotherapy was the focus of three articles, where the successful adjustment of treatments to meet the specific needs of the individuals resulted in positive outcomes ( Delany et al. , 2023 ; Enomoto et al. , 2015 ; Sleijfer et al. , 1996 ). An article with a focus on radiation therapy showed that anaesthesia could be used to improve treatment tolerance ( Gandhidasan et al. , 2020 ). A standard approach to cancer surgery for those with and without intellectual disability showed that similar results were achievable ( Ishimaru et al. , 2022 ). A study which investigated pain management for cancer individuals found that people with an intellectual disability were less likely to receive opioids, compared to their peers in the general population ( Segerlantz et al. , 2019 ). The authors proposed that this lack of treatment was due to communication challenges rather than the absence of pain. Concerningly, a case study on a stem transplant for a patient with intellectual disability who lacked the understanding of the procedure, resulted in premature death and unwarranted suffering ( Brown, 2011 ). Some overlap was observed within studies where other treatments were also incorporated. (d) Ethical practice Ethical practice was the final broad theme, which included autonomy, where individuals with an intellectual disability were able to decide on their own treatment options e. Patient autonomy explored the unique role of care partners and their roles in supporting this population in health matters. More positive outcomes and meaningful engagement were seen with the proactive engagement of the patient in their own care while not updating the patient on their condition resulted in needless distress and an early death ( Brown, 2011 ; Flynn et al. , 2016 ). Studies also discussed the principle of “truth-telling” which is when healthcare providers and care partners determine how much, if at all they decide to explain to the patient about their diagnoses ( Bernal & Tuffrey-Wijne, 2008 ). Patient autonomy highlighted the ethical debates that surround consent and individuals with an intellectual disability ( Brown, 2011 ; Bernal & Tuffrey-Wijne, 2008 ; Flynn et al. , 2016 ). Lastly, an equality in the distribution of prescription pain medication was observed, where older adults with cancer and intellectual disability were less likely to be prescribed pain medications then their general population peers resulting in the under-management of pain and a reduction in quality of life ( Segerlantz et al. , 2019 ). Discussion This literature review examines the cancer diagnostic approaches and treatments available for adults with intellectual disability and any associated barriers or enablers. Results identified the importance of tailored education and information and application to cancer screening, diagnosis and treatment, and more involvement of adults with intellectual disability in decisions about their own care, on positive impacts on their cancer outcomes. Unique barriers to screening access were identified. Overall, the high number of individual case studies and the low numbers of people with intellectual disability in cancer studies is indicative of an under-researched area. Although the average lifespan of people with intellectual disability has increased, as theoretically has the risk for cancer developing, they are still not receiving equitable screening to the general population ( Flynn et al. , 2016 ; Lai et al. , 2014 ; Mahar et al. , 2024 ; Satgé et al. , 2014 ; Wilkinson et al. , 2011 ). By utilising secondary prevention, to diagnose cancer while it is still asymptomatic, cancer may be diagnosed earlier while it is still possible to have positive health outcomes ( Ouellette‐Kuntz et al. , 2015a ). Nevertheless, individuals with intellectual disability may be unable to recognise signs and symptoms suggestive of cancer or be able to communicate their symptoms to a caregiver, and the caregiver may be unable to recognise symptoms which could make them more easily overlooked unless regular checks occur ( Ouellette-Kuntz et al. , 2015a ). A key risk factor for cancer is ageing, and screening for cancer detection is recommended at specific ages. Historically, the intellectual disability population had shorter lifespans, and many would not reach the age when preventative measures commenced and therefore were excluded from standard screening ( Flynn et al. , 2016 ; Lai et al. , 2014 ; Mahar et al. , 2024 ; Satgé et al. , 2014 ; Wilkinson et al. , 2011 ). However, people with intellectual disability may not receive necessary cancer screening due to a unique set of barriers ( Bates & Triantafyllopoulou, 2019 ; Delany et al. , 2023 ; Ouellette-Kuntz et al. , 2015b ). Where people resided was identified as a barrier to screening access ( Sullivan et al. , 2003 ; Xu et al. , 2017 ). People who lived in institutionalised care facilities had less screening levels, perhaps due to higher levels of intellectual disability and less resources at the facility ( Armin et al. , 2022 ; Sullivan et al. , 2003 ). Additionally, if a patient lives alone in a rural environment, a geographical influence is seen where transportation to screening may be difficult, often leading to less screening attendance ( Yen et al. , 2014 ). Conversely, one study showed a protective factor for those who resided in a group home or medical facility, where they were more likely to receive cancer screening due to established policies and procedures ( Xu et al. , 2017 ). Elevated rates of late diagnosis are reported for people with intellectual disability compared to the general population. Studies indicate that individuals with intellectual disability were more likely to detect breast, colorectal, and lung cancer at stages III and IV rather than stages I or II ( Mahar et al. , 2024 ; Satgé et al. , 2023 ). These late-stage diagnoses of cancers meant that only limited treatments were available, and a high mortality rate occurred. Furthermore, people with intellectual disability have an onset of tumours at earlier ages than that of the general population, so normal screening timelines are inadequate for a timely diagnosis ( Heslop et al. , 2022 ; Mahar et al. , 2024 ). Cognitive deficits associated with intellectual disability may make understanding cancer screening procedures or communicating with relevant specialists more difficult, which can heighten stress and anxiety surrounding procedures, resulting in their cancellation ( Bates & Triantafyllopoulou, 2019 ; Horsbøl et al. , 2023 ; Wilkinson et al. , 2011 ). A need for education and tailored information-on cancer screening was identified as critically important, to enable a person with intellectual disability to engage with screening. Many individuals with intellectual disability are not educated about the need for cancer screening or the processes involved, and often do not feel prepared to attend screening, which reduces uptake ( Wilkinson et al. , 2011 ). A lack of education and preparation has contributed to large gaps in cancer screening ( Ishimaru et al. , 2022 ). Females with intellectual disability expressed feelings of confusion, and felt they could not communicate their emotions with their providers and that their doctors did not understand the extent of their confusion ( Wilkinson et al. , 2011 ). Furthermore, individuals with intellectual disability felt they were misinformed or given inadequate information about screening procedures resulting in inadequate preparation. Results suggested that health professionals should take the time to explain to individuals with intellectual disability the specific details of procedures and provide additional support options such as videos for clarity ( Sullivan et al. , 2003 ; Wilkinson et al. , 2011 ). A link between higher levels of education and information on cancer screening and higher levels of screening engagement has been observed which indicates a focus on appropriate education, information and reasonable adjustments for people with intellectual disability is necessary to increase cancer knowledge, confidence and screening participation rates ( Armin et al. , 2022 ; Greenwood et al. , 2014 ; Swaine et al. , 2014 ; Wang et al. , 2015 ; Wilson et al. , 2018 ). While education and information on cancer screening and treatment for carers and those with intellectual disability is an important foundation for supporting individuals with intellectual disability, it is crucial that this is provided in conjunction with adaptations for cancer treatments ( Armin et al. , 2023 ). Case studies have demonstrated that modified chemotherapy regimens are feasible for the successful treatment of cancer for individuals with intellectual disability and concluded that following evidence-based practice is not always the best route of cancer care for individuals with intellectual disability, and that health care providers need to take time to make the necessary care adjustments ( Delany et al. , 2023 ; Enomoto et al. , 2015 ). These case studies, while limited in numbers, demonstrated that individuals with intellectual disability should be considered for chemotherapy treatments, and providers should tailor treatment and care to their specific needs. Radiation and surgery are often an integral part of cancer treatment. Both have been successfully adapted and employed in individuals with intellectual disability, where individualised care based on the unique needs of the individuals with intellectual disability was considered ( Gandhidasan et al. , 2020 ; Ishimaru et al. , 2022 ). While there are ethical debates about men with testicular cancer undergoing radical inguinal orchidectomy for both diagnosis and treatment, the cure rate can be increased by finding an appropriate balance of therapy ( Hafeez et al. , 2015 ). Indeed, ethical principles play a large role in the type of cancer treatment that individuals with intellectual disability receive. A case study on a stem cell transplant largely focussed on treatment ethics, although this known risky therapy was not proven to be successful because of the complications the patient experienced, independent of the presence of an intellectual disability ( Brown, 2011 ). Similarly, studies explored debates regarding pain management and prescription drugs being used in the treatment of individuals with intellectual disability ( Axmon et al. , 2018 ; El-Tallawy et al. , 2023 ; Millard & de Knegt, 2019 ; Segerlantz et al. , 2019 ). Older adults with cancer and intellectual disability were less likely to receive prescription pain medications then their counterparts resulting in the under-management of pain and a reduction in quality of life ( Segerlantz et al. , 2019 ). The ethical debate of treating cancer individuals with intellectual disability continues into the theme of autonomy. Having an intellectual disability may inhibit an individual's understanding of a plethora of topics which may further alter how decisions are made ( Hafeez et al. , 2015 ). Nonetheless, the intellectual disability community has a long history of debating how to handle decision-making and notifying individuals with intellectual disability of different diagnoses, especially when it comes to cancer, complicated by individual country legal frameworks and capacity ( Delany et al. , 2023 ; Kiani et al. , 2014 ; Tuffrey-Wijne et al. , 2010 ). Often people with intellectual disability have difficulties being independent and may have carers who have influence over their medical, educational, and financial decisions ( Kiani et al. , 2014 ). A lack of truth-telling stems from wanting to protect the patient from excess anxiety and distress, though it may limit the patient’s autonomy. However, there is a lack of evidence about distress after cancer diagnosis in individuals with intellectual disability, implying that these individuals should be entitled to honesty when it comes to their care and making medical decisions ( Bernal & Tuffrey-Wijne, 2008 ; Flynn et al. , 2016 ). Furthermore, medical professionals participated in non- “truth-telling” due to feelings of discomfort when working with this population, and they conferred solely with care partners about the patient's condition rather than with the patient themselves ( Flynn et al. , 2016 ; Tuffrey-Wijne et al. , 2010 ). Studies also found evidence where carers have asked for the professionals to discuss diagnosis with the individuals and the professionals refused, most likely due to a lack of confidence or understanding of intellectual disability. Brown explains an ethical dilemma where a patient who was unable to consent for themselves underwent aggressive treatment, in line with best practice, despite doubts raised by nursing staff ( Brown, 2011 ). The patient passed away from pneumonia within a year of treatment, which brings into question the overall suitability of the treatment. Informed consent is a demonstrated successful consent method for individuals with intellectual disability and should be used as part of a standard protocol. These findings may serve as a guide for healthcare professionals in providing diagnostic and treatment options, educating their patients, and communicating with individuals with intellectual disability about their illness. Cancer patients with intellectual disability need to have their voices included in the research. Conclusion This literature review highlights substantial disparities in treatment and diagnosis needs in cancer individuals with intellectual disability and their general population peers with implications for policy and practice. It provides evidence of the lack of research in the area where case studies dominate and the urgent need to cater for this underserved, underrepresented population. Unique barriers to screening including living conditions, age, life span and communication difficulties, contributed to later diagnosis and worse cancer outcomes. This review demonstrates that people with intellectual disability should be provided with more education and adapted communication like easy-read materials on cancer screening and treatment options and should have access to screening at earlier ages. Finally, this literature review showed that in order to preserve ethical principles, people with intellectual disability should be provided with more tailored treatment options, their autonomy should be given due consideration and open and honest communication should be practiced, which could improve their cancer diagnosis and treatment outcomes. In summary, these findings support the need for coordinated clinical and policy-level efforts to reduce inequities and improve cancer outcomes for this underserved population. Limitations This literature review has several limitations including an over reliance on case studies with the heterogeneity of study designs making synthesis more challenging. Given the extensive body of literature, it is possible that some relevant studies were not included. Additionally, cancer diagnosis and treatment may have a geographical residential influence which may impact study findings. Equally, the subjective nature of thematic analysis may affect the interpretation and applicability of findings. Lastly, aged results are reported due to a dearth of recent evidence. Funding Statement This research was supported by the University of Pennsylvania Global Research and Internship Program and Trinity College School of Nursing and Midwifery. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. [version 3; peer review: 2 approved, 1 approved with reservations] Data availability Underlying data No data were associated with this article Extended data Harvard Dataverse- Replication Data for: Table 4: Article extraction summary information https://doi.org/10.7910/DVN/VD23QF ( Lynch, 2025 ) Data available under CC0 1.0 licence References Armin JS, Williamson HJ, Begay A, et al. : Adapting a cancer screening education program for Native American women with disabilities. 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BMC Health Serv Res. 2014;14(1): 240. 10.1186/1472-6963-14-240 [ DOI ] [ PMC free article ] [ PubMed ] [ Google Scholar ] HRB Open Res. 2026 Apr 23. doi: 10.21956/hrbopenres.15890.r54650 Reviewer response for version 3 Kumaresan Cithambaram Kumaresan Cithambaram 1 Technological University of the Shannon, Athlone, Ireland Referee Find articles by Kumaresan Cithambaram 1 Author information Copyright and License information 1 Technological University of the Shannon, Athlone, Ireland Competing interests: No competing interests were disclosed. Roles Kumaresan Cithambaram : Referee Copyright: © 2026 Cithambaram K This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. PMC Copyright notice The authors have addressed all comments and queries satisfactorily. I recommend approval for Indexing. Are the rationale for, and objectives of, the Systematic Review clearly stated? Yes Is the statistical analysis and its interpretation appropriate? Not applicable Are sufficient details of the methods and analysis provided to allow replication by others? Yes Are the conclusions drawn adequately supported by the results presented in the review? Yes Reviewer Expertise: Palliative care, intellectual disability, end-of-life care, migrant health, systematic review. I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard. HRB Open Res. 2026 Mar 18. doi: 10.21956/hrbopenres.15784.r53851 Reviewer response for version 2 Kumaresan Cithambaram Kumaresan Cithambaram 1 Technological University of the Shannon, Athlone, Ireland Referee Find articles by Kumaresan Cithambaram 1 Author information Copyright and License information 1 Technological University of the Shannon, Athlone, Ireland Competing interests: No competing interests were disclosed. Roles Kumaresan Cithambaram : Referee Copyright: © 2026 Cithambaram K This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. PMC Copyright notice Thank you for the opportunity to review this paper. The objectives and rationale of the review are clearly outlined, and the paper provides insight into the needs of, and support for, people with intellectual disabilities when they receive screening related to cancer diagnosis and treatment. The methodology is clearly described and follows the PRISMA Guidelines, and the conclusions are appropriately drawn from the review findings. However, several suggestions are offered below to strengthen the manuscript. Abstract: Background: Consider revising “diagnostic tools” to “diagnostic procedures.” The review seems to address access to diagnostic processes rather than specific tools, so access to diagnostic procedures and treatments may be a clearer and more accurate description. Method: Consider replacing “analysis” with “synthesis,” as synthesis is generally the more appropriate term in the context of literature or systematic reviews, where findings from multiple studies are integrated rather than analysed as primary data. Results: There appears to be an inconsistency between the abstract and the findings section. The findings describe “ethical issues” as a theme, while the abstract refers to “autonomy.” The results section of the abstract should be revised to reflect the themes reported in the findings. Introduction Check citation style: Loud & Murphy (2017) or ( Loud & Murphy, 2017) Paragraph 2 The statement “there appear to be misassumptions that women with intellectual disability do not require cervical screening” requires further clarification. Please specify whose assumptions are being referred to (e.g., healthcare professionals, family members, or caregivers) and explain the basis of these assumptions. For example, are they related to beliefs that women with intellectual disability are not sexually active? This would benefit from further explanation and discussion. The description of diagnostic overshadowing appears inaccurate. Diagnostic overshadowing refers to healthcare professionals misattributing physical symptoms to a person’s intellectual disability rather than investigating possible medical causes. Please review and revise this explanation. This statement requires supporting evidence “While the reasons why they are developing late-stage cancer at earlier ages have not yet been established, studies suggest that lowering screening ages for people with intellectual disability could be beneficial for earlier diagnosis” This statement requires supporting evidence “The prognosis for cancer patients is dependent on the cancer stage at diagnosis, so a later diagnosis in patients with intellectual disability could be a key factor accounting for differences in mortality rates” Methods: Eligibility Criteria The acronym PICOS may not be appropriate for this review. PICOS is typically used to compare interventions and outcomes, whereas this review does not compare across different living environments, and the outcome does not measure cancer itself. Rather, the review aims to identify barriers and enablers to access to cancer diagnostic procedures and treatment. Consider using the PICoS framework instead: P – Population: Adults with intellectual disability I – Intervention: Cancer diagnostic procedures and treatment Co – Context: Barriers and enablers influencing access to cancer diagnostic procedures and treatment S – Study type Consider revising the framework to PICoS or another more appropriate acronym that reflects the focus of the review. Screening Procedure PRISMA flow diagram: Please review the numbers reported at each stage, as there appear to be inconsistencies. Data extraction Please include a discussion of how the data extraction table was developed, who conducted the data extraction, and how discrepancies between reviewers were resolved. Thematic Analysis Consider replacing “analysis” with “thematic synthesis,” as this term is more appropriate for review methodology. Please also include a discussion on who conducted the synthesis and how codes and themes were developed and agreed. Results Statement “see Table 4a and Table 4 in extended data” Table 4 repeated. Ethical Issues Remove “e” at the end of the sentence “Ethical practice was the final broad theme, which included autonomy, where patients with an intellectual disability were able to decide on their own treatment options e” Consider using “individuals” or “adults with intellectual disability” rather than “patients,” where appropriate, to maintain person-centred language. Consider replacing “medical providers” with “healthcare professionals,” “medical professionals,” or “healthcare providers.” Discussion The discussion section would benefit from being more focused. Please tighten this section to concentrate on the themes identified in the review and support these with relevant literature. Some parts of the discussion are quite broad and repeat points already presented in the introduction, for example: “Although the average lifespan of people with intellectual disability has increased, and theoretically the risk of cancer has also increased, they are still not receiving screening at the same rate as the general population.” A sentence begins with “A link between higher levels of education…” . Please clarify what is meant by “higher levels of education.” Does this refer to higher educational qualifications or to greater knowledge and understanding of cancer screening and information? This should be clarified. The sentence “While education is an important foundation for supporting patients with intellectual disability, it is crucial that this is provided in conjunction with adaptations for cancer treatments” requires clarification. Please specify who the education is intended for. Does this refer to education for individuals with intellectual disability, or training/education for healthcare professionals and caregivers supporting them? Consider including a section on the implications of the review, outlining how the findings contribute to practice, research, and policy. I suggest using the term “education” carefully throughout the paper to clarify that it refers to education and information related to cancer screening and treatment, rather than the educational level of adults with intellectual disability. Are the rationale for, and objectives of, the Systematic Review clearly stated? Yes Is the statistical analysis and its interpretation appropriate? Not applicable Are sufficient details of the methods and analysis provided to allow replication by others? Yes Are the conclusions drawn adequately supported by the results presented in the review? Yes Reviewer Expertise: Palliative care, intellectual disability, end-of-life care, migrant health, systematic review. I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above. HRB Open Res. 2026 Mar 30. Louise Lynch Louise Lynch 1 Trinity College Dublin, Ireland Find articles by Louise Lynch 1 Author information Copyright and License information 1 Trinity College Dublin, Ireland Competing interests: No competing interests were disclosed. PMC Copyright notice Thank you for your feedback and taking the time to review our article. We have incorporated your feedback (if it was not already included in the latest version) which included adding the correct themes in the abstract, changing words (eg patients to individuals, tools to procedures), replacing PICOS with PICoS and updating the Primsa diagram. With reference to changing 'analysis' to 'synthesis', while we understand your reasoning, using Braun and Clarke for qualitative data looks at identifying, analysing, and interpreting patterns of meaning i.e. overall themes within data. Because of this it is a flexible, interpretive method rather than a systematic synthesis of the existing literature. Hence we feel  that analysis should remain and hope that you understand our reasoning. HRB Open Res. 2026 Feb 26. doi: 10.21956/hrbopenres.15784.r53786 Reviewer response for version 2 Kevin M Korous Kevin M Korous 1 Medical College of Wisconsin, WI, USA Referee Find articles by Kevin M Korous 1 Author information Copyright and License information 1 Medical College of Wisconsin, WI, USA Competing interests: No competing interests were disclosed. Roles Kevin M Korous : Referee Copyright: © 2026 Korous KM This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. PMC Copyright notice The author responded thoroughly to my comments and I appreciate that they were open to a discussion. I have no further comments to make. Are the rationale for, and objectives of, the Systematic Review clearly stated? No Is the statistical analysis and its interpretation appropriate? Yes Are sufficient details of the methods and analysis provided to allow replication by others? Partly Are the conclusions drawn adequately supported by the results presented in the review? Partly Reviewer Expertise: Systematic reviews, meta-analysis, child development, public health, cancer screening I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard. HRB Open Res. 2025 Aug 27. doi: 10.21956/hrbopenres.15576.r48236 Reviewer response for version 1 Kevin M Korous Kevin M Korous 1 Medical College of Wisconsin, WI, USA Referee Find articles by Kevin M Korous 1 Author information Copyright and License information 1 Medical College of Wisconsin, WI, USA Competing interests: No competing interests were disclosed. Roles Kevin M Korous : Referee Copyright: © 2025 Korous KM This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. PMC Copyright notice Summary The authors conducted a literature review to examine which factors contribute to routine cancer screening among individuals with intellectual disabilities. The strength of this study is their focus on a specific, less researched population and I appreciate their use of a literature review to incorporate case studies into the larger picture of evidence. The contribution of this review can be strengthened by addressing the following major and minor limitations. Major Limitations I suggest that the authors clearly distinguish their paper as a literature review or a systematic review, and subsequently strengthen the rationale. While both methodologies are relatively similar in the overall goal the distinction has implications for evaluating the quality and contribution of the publication. As you will see, many of my comments are from the perspective that it is a systematic review. For instance, I was not sold that a systematic review was necessary aside from the fact that there were little to no published systematic reviews on this topic. If it is intended to be a systematic review, I encourage the authors to articulate the benefits of a systematic review to the gap in literature compared to just a literature review, ultimately helping readers better understand its contribution. The authors reported a huge drop in the number of articles included compared to the number identified in their search strategy. While common in systematic reviews, the significant drop does suggest that the search terms could have been more specific. Also, nearly a third of articles were identified through citation searchers, meaning that the search terms could have been more sensitive. Perhaps the authors could use this opportunity to guide future systematic reviews on how to develop sensitive and specific search terms and keywords for identifying research studies on cancer treatment and diagnosis among the population of focus. In other words, what did the authors learn from their search process? Why didn’t the search terms identify the articles retrieved from relevant reviews? I recommend that the authors sell the contribution of their review more than they currently do. There is very little discussion on the contribution of the systematic review beyond the studies they included and reviewed. To resolve this issue, the authors could point out the gaps in the literature and what future research or practitioners could do to address such gaps. As the reviewers, the authors are uniquely positioned to address the barriers and advance the literature. There's no discussion of the full picture of evidence, what gaps are present Minor Limitations Abstract does not clearly state the purpose or aim of the literature. Add dates of search and any major criteria in the method of the abstract. Note how many studies were included in the results of abstract. On page 4, under Search Strategy the authors note that relevant reviews were searched. Please cite these reviews. It was not clear why the authors exclude reviews and book chapters from the review. If the goal was to examine all factors related to cancer diagnosis and treatment among individual with intellectual disabilities, then reviews and book chapters would have contributed to this conversation. For instance, book chapter may include additional case studies. I recommend that the authors add stronger justification for this exclusion or consider including these types of publications. Table 2 was referenced for the list of study characteristics, but Table 2 was the list of keywords and Table 4 had the characteristics. Nonetheless, some factors discussed in the article were not included in Table 4 (e.g., level of ID, measurement method, outcome). I recommend addressing the sample size gap between the included studies because without it, readers will overlook the fact that most studies on ID are small, and some are single case studies. What does this tell readers about the state of the literature? There were only 3 studies for autonomy, therefore, it was unclear why autonomy was labeled as a major theme across the 35 studies. On page 7, living circumstances was described as a both a barrier and a protective factor. It seems odd to label this factor as both unless it is a barrier for some individuals and a protective factor for others; in this case, I recommend that the authors identify the moderating factor in that situation which causes living circumstances to switch its influence. Otherwise, I recommend that the authors stick to one or the other. Paragraphs 2 and 3 of the discussion read more like an introduction section, perhaps the authors can move those paragraphs. On page 7, “Both the educational programmed and the information leaflet were determined to have a positive effect on individuals’ knowledge and confidence in performing a testicular self-examination.” I recommend that the authors add to this how much these interventions improved knowledge and confidence (e.g., a small shift versus a large jump). Did education about concern screening address any of the barriers to obtain screening? Although these themes were separate, it may be helpful to note where these themes overlapped. The paragraphs within the first column of page 8 do a really great job at incorporating the findings of the review to the broader research. Last paragraph on page 8 brought up ethics as an important factor in cancer treatment and was weaved in some of the themes (e.g., autonomy). I suggest that the authors consider including ethical practices as its own theme as it seems like a special topic that could add to the literature more than the current themes. Page 9, regarding limitation “Additionally, cancer diagnosis and treatment may have a geographical influence which may impact study findings.” It wasn’t clear what the geographical limitation was as this was not discussed in the results. The final paragraph sells the literature review by suggesting it shows that people with ID should be provided more education, have access to earlier screening, and have more tailored treatment. This conclusion, however, applies to many populations and could be arrived at without a literature review as it is sort of predictable. What is the substantial contribution of this review? Page 9 brings up non-“truth-telling”, which caught my attention as a unique contribution and could have been given more attention because it is a behavior/practice that could potentially be changed to improve diagnosis and treatment. Are the rationale for, and objectives of, the Systematic Review clearly stated? No Is the statistical analysis and its interpretation appropriate? Yes Are sufficient details of the methods and analysis provided to allow replication by others? Partly Are the conclusions drawn adequately supported by the results presented in the review? Partly Reviewer Expertise: Systematic reviews, meta-analysis, child development, public health, cancer screening I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above. HRB Open Res. 2025 Aug 18. doi: 10.21956/hrbopenres.15576.r48116 Reviewer response for version 1 Rebecca Hansford Rebecca Hansford 1 Queen's University, Kingston, Canada Referee Find articles by Rebecca Hansford 1 Author information Copyright and License information 1 Queen's University, Kingston, Canada Competing interests: No competing interests were disclosed. Roles Rebecca Hansford : Referee Copyright: © 2025 Hansford R This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. PMC Copyright notice Overall The authors should be consistent with wording- e.g., intellectual disability or intellectual disabilities. Abstract In the background, differences or challenges in providing consent would be more appropriate than the inability to provide consent. Namely, there are individuals with intellectual disability who do provide consent for healthcare-related decisions. Introduction Para 2: Similar comment regarding inability to provide consent- perhaps challenges in providing consent would be more suitable. Methods Missing a period after this sentence: “Literature reviews provide a thorough critique and examination of all the evidence available on the topic and facilitate a descriptive analysis and meaningful synthesis of the current available research (Colquhoun et al., 2014)”. Why was a literature review selected rather than a more formal type of review (e.g., scoping, etc.)? The authors should consider extracting information on cancer site from the articles as well- this was conducted somewhat in Table 4, but having a separate extraction item could be useful, and then summarized in the results. Results Table 4, which includes all the extracted information (author, year, country, study aim, study design, sample size, age, gender, level of intellectual disability, diagnosis or treatment, measurement method, outcome, summary, conclusions), should potentially be included in the main article rather than the supplementary files. Table 4- There is a red comma after Armin, rather than black. 35 studies were included in the PRISMA table, but I only noted 26 listed in Table 4. The authors should update this Table accordingly. The authors should consider adding more details regarding extracted information in a narrative summary at the beginning of the results. For example, how many studies were each type of study design? How many of the studies were quantitative, qualitative, etc? Consequently, there was information about the included studies introduced in the discussion, which could have been mentioned in the results when narratively summarizing the studies. There are two studies that I do not see in the reference list that were published during the study time frame that could be applicable (Brown et al., 2016; Cobigo et al., 2013). I wonder if the authors should add these to the review and reflect on whether it is possible that any other relevant studies were missed. Brown, H., Plourde, N., Ouellette-Kuntz, H., Vigod, S., & Cobigo, V. (2016). Brief report: cervical cancer screening in women with intellectual and developmental disabilities who have had a pregnancy. Journal of Intellectual Disability Research . https://doi.org/10.1111/jir.12225 Cobigo, V., Ouellette-Kuntz, H., Balogh, R., Leung, F., Lin, E., & Lunksy, Y. (2013). Are cervical and breast cancer screening programmes equitable? The case of women with intellectual and developmental disabilities. Journal of Intellectual Disability Research , 57 (5), 478-488. https://doi.org/10.1111/jir.12035 Discussion As noted in #9, I wonder if some information about studies could have been summarized narratively in the results, allowing for a more focused discussion on barriers, facilitators, etc., in the discussion. One example would be how the authors summarized how adults with intellectual disability were 5 times as likely to never be screened compared to those without intellectual disability (Ishimaru et al., 2022; Lai et al., 2014). While these articles were included in the review, this information was not mentioned until the discussion, and perhaps it would have been more appropriate to note some of these findings from the studies in the results, allowing for a deeper look into why disparities are occurring in the discussion. Are the rationale for, and objectives of, the Systematic Review clearly stated? Yes Is the statistical analysis and its interpretation appropriate? Yes Are sufficient details of the methods and analysis provided to allow replication by others? Yes Are the conclusions drawn adequately supported by the results presented in the review? Yes Reviewer Expertise: Epidemiology, quantitative research, qualitative research, mixed methods research, intellectual or developmental disabilities, cancer I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above. References 1. : Brief report: cervical cancer screening in women with intellectual and developmental disabilities who have had a pregnancy. Journal of Intellectual Disability Research .2016;60(1) : 10.1111/jir.12225 22-27 10.1111/jir.12225 [ DOI ] [ Google Scholar ] 2. : Are cervical and breast cancer screening programmes equitable? The case of women with intellectual and developmental disabilities. Journal of Intellectual Disability Research .2013;57(5) : 10.1111/jir.12035 478-488 10.1111/jir.12035 [ DOI ] [ Google Scholar ] HRB Open Res. 2026 Jan 15. Louise Lynch Louise Lynch 1 Trinity College Dublin, Ireland Find articles by Louise Lynch 1 Author information Copyright and License information 1 Trinity College Dublin, Ireland Competing interests: none PMC Copyright notice Thank you both for taking the time to review our article and providing such valuable insights. Responses to each individual comment are included below in bold italics . An updated version of the article will be submitted. Reviewer 1 Overall The authors should be consistent with wording- e.g., intellectual disability or intellectual disabilities. Amended. Apologies. Abstract In the background, differences or challenges in providing consent would be more appropriate than the inability to provide consent. Namely, there are individuals with intellectual disability who do provide consent for healthcare-related decisions. Noted and amended. Introduction Para 2: Similar comment regarding inability to provide consent- perhaps challenges in providing consent would be more suitable. Noted and amended. Methods Missing a period after this sentence: “Literature reviews provide a thorough critique and examination of all the evidence available on the topic and facilitate a descriptive analysis and meaningful synthesis of the current available research (Colquhoun et al., 2014)”. Added Why was a literature review selected rather than a more formal type of review (e.g., scoping, etc.)? A literature review was selected to facilitate a broad general search on the topic so that results could be synthesised. The authors should consider extracting information on cancer site from the articles as well- this was conducted somewhat in Table 4, but having a separate extraction item could be useful, and then summarized in the results. Apologies we did not feel that this level of detail was needed for this paper as the foucs was on the screening and not the site specific cancers. Results Table 4, which includes all the extracted information (author, year, country, study aim, study design, sample size, age, gender, level of intellectual disability, diagnosis or treatment, measurement method, outcome, summary, conclusions), should potentially be included in the main article rather than the supplementary files. Table 4 included with relevant information Table 4- There is a red comma after Armin, rather than black. amended 35 studies were included in the PRISMA table, but I only noted 26 listed in Table 4. The authors should update this Table accordingly. Amended and two additional articles as recommended were added to bring total to 28. The authors should consider adding more details regarding extracted information in a narrative summary at the beginning of the results. For example, how many studies were each type of study design? How many of the studies were quantitative, qualitative, etc? Consequently, there was information about the included studies introduced in the discussion, which could have been mentioned in the results when narratively summarizing the studies. Amended and moved details as recommended. There are two studies that I do not see in the reference list that were published during the study time frame that could be applicable (Brown et al., 2016; Cobigo et al., 2013). I wonder if the authors should add these to the review and reflect on whether it is possible that any other relevant studies were missed. Apologies these were screened out by mistake. Added now. Others may have been missed and added in as a limitation. Discussion As noted in #9, I wonder if some information about studies could have been summarized narratively in the results, allowing for a more focused discussion on barriers, facilitators, etc., in the discussion. One example would be how the authors summarized how adults with intellectual disability were 5 times as likely to never be screened compared to those without intellectual disability (Ishimaru et al., 2022; Lai et al., 2014). While these articles were included in the review, this information was not mentioned until the discussion, and perhaps it would have been more appropriate to note some of these findings from the studies in the results, allowing for a deeper look into why disparities are occurring in the discussion. Thank you. The authors have edited the discussion and results with this in mind. Reviewer 2 Summary The authors conducted a literature review to examine which factors contribute to routine cancer screening among individuals with intellectual disabilities. The strength of this study is their focus on a specific, less researched population and I appreciate their use of a literature review to incorporate case studies into the larger picture of evidence. The contribution of this review can be strengthened by addressing the following major and minor limitations. Thank you. Major Limitations I suggest that the authors clearly distinguish their paper as a literature review or a systematic review, and subsequently strengthen the rationale. While both methodologies are relatively similar in the overall goal the distinction has implications for evaluating the quality and contribution of the publication. As you will see, many of my comments are from the perspective that it is a systematic review. For instance, I was not sold that a systematic review was necessary aside from the fact that there were little to no published systematic reviews on this topic. If it is intended to be a systematic review, I encourage the authors to articulate the benefits of a systematic review to the gap in literature compared to just a literature review, ultimately helping readers better understand its contribution. Apologies for not making this clearer. This is not a systematic review but a standard literature review. Details have been added in the methodology in the main text and abstract. This is also included in the title. The authors reported a huge drop in the number of articles included compared to the number identified in their search strategy. While common in systematic reviews, the significant drop does suggest that the search terms could have been more specific. Also, nearly a third of articles were identified through citation searchers, meaning that the search terms could have been more sensitive. Perhaps the authors could use this opportunity to guide future systematic reviews on how to develop sensitive and specific search terms and keywords for identifying research studies on cancer treatment and diagnosis among the population of focus. In other words, what did the authors learn from their search process? Why didn’t the search terms identify the articles retrieved from relevant reviews? The authors used broad search terms in the hope of finding all available information as previous experience has shown that potentially limited information is available. The disadvantage of this as you correctly pointed out was a lot of irrelevant information which needed to be screened. I recommend that the authors sell the contribution of their review more than they currently do. There is very little discussion on the contribution of the systematic review beyond the studies they included and reviewed. To resolve this issue, the authors could point out the gaps in the literature and what future research or practitioners could do to address such gaps. As the reviewers, the authors are uniquely positioned to address the barriers and advance the literature. There's no discussion of the full picture of evidence, what gaps are present. The discussion has been amended and hopefully provides a better reflection of the state of the literature. Minor Limitations Abstract does not clearly state the purpose or aim of the literature. Added Add dates of search and any major criteria in the method of the abstract. Added Note how many studies were included in the results of abstract. Added On page 4, under Search Strategy the authors note that relevant reviews were searched. Please cite these reviews. Apologies these are unavailable. It was not clear why the authors exclude reviews and book chapters from the review. If the goal was to examine all factors related to cancer diagnosis and treatment among individual with intellectual disabilities, then reviews and book chapters would have contributed to this conversation. For instance, book chapter may include additional case studies. I recommend that the authors add stronger justification for this exclusion or consider including these types of publications. The authors focussed on original research to reduce bias. However, as you pointed out the relevant reviews were searched for original content. Table 2 was referenced for the list of study characteristics, but Table 2 was the list of keywords and Table 4 had the characteristics. Nonetheless, some factors discussed in the article were not included in Table 4 (e.g., level of ID, measurement method, outcome). Apologies. Table numbers changed and amended. I recommend addressing the sample size gap between the included studies because without it, readers will overlook the fact that most studies on ID are small, and some are single case studies. What does this tell readers about the state of the literature? A separate limitation section has been added highlighting the overreliance on case studies in this population. There were only 3 studies for autonomy, therefore, it was unclear why autonomy was labeled as a major theme across the 35 studies. The theme name has been changed to ethical practice which has meant that two additional studies are not included in this theme. On page 7, living circumstances was described as a both a barrier and a protective factor. It seems odd to label this factor as both unless it is a barrier for some individuals and a protective factor for others; in this case, I recommend that the authors identify the moderating factor in that situation which causes living circumstances to switch its influence. Otherwise, I recommend that the authors stick to one or the other. This has been reworded and reordered for clarity. Paragraphs 2 and 3 of the discussion read more like an introduction section, perhaps the authors can move those paragraphs. These have been changed and portions moved and deleted. On page 7, “Both the educational programmed and the information leaflet were determined to have a positive effect on individuals’ knowledge and confidence in performing a testicular self-examination.” I recommend that the authors add to this how much these interventions improved knowledge and confidence (e.g., a small shift versus a large jump). We reworded the section and this has been deleted. Did education about concern screening address any of the barriers to obtain screening? Although these themes were separate, it may be helpful to note where these themes overlapped. Yes, an increase in screening participation was observed but not quantitatively. Modified sentence to include ‘participation’. Shortened the section overall. The paragraphs within the first column of page 8 do a really great job at incorporating the findings of the review to the broader research. Thank you. Last paragraph on page 8 brought up ethics as an important factor in cancer treatment and was weaved in some of the themes (e.g., autonomy). I suggest that the authors consider including ethical practices as its own theme as it seems like a special topic that could add to the literature more than the current themes. Thank you. This is a really good idea that we did not consider. We have changed the autonomy theme name to ethical practice, which has increased the number of studies in this theme to 5. Page 9, regarding limitation “Additionally, cancer diagnosis and treatment may have a geographical influence which may impact study findings.” It wasn’t clear what the geographical limitation was as this was not discussed in the results. Apologies this was in relation to rural living. ‘Residential location’ has been added for clarity. The final paragraph sells the literature review by suggesting it shows that people with ID should be provided more education, have access to earlier screening, and have more tailored treatment. This conclusion, however, applies to many populations and could be arrived at without a literature review as it is sort of predictable. What is the substantial contribution of this review? Amended. Page 9 brings up non-“truth-telling”, which caught my attention as a unique contribution and could have been given more attention because it is a behavior/practice that could potentially be changed to improve diagnosis and treatment. Thank you. This is a great point and has been added to conclusion. Associated Data This section collects any data citations, data availability statements, or supplementary materials included in this article. Data Availability Statement Underlying data No data were associated with this article Extended data Harvard Dataverse- Replication Data for: Table 4: Article extraction summary information https://doi.org/10.7910/DVN/VD23QF ( Lynch, 2025 ) Data available under CC0 1.0 licence Articles from HRB Open Research are provided here courtesy of Health Research Board Ireland ACTIONS View on publisher site PDF (815.2 KB) Cite Collections Permalink PERMALINK Copy RESOURCES Similar articles Cited by other articles Links to NCBI Databases Cite Copy Download .nbib .nbib Format: AMA APA MLA NLM Add to Collections Create a new collection Add to an existing collection Name your collection * Choose a collection Unable to load your collection due to an error Please try again Add Cancel Follow NCBI NCBI on X (formerly known as Twitter) NCBI on Facebook NCBI on LinkedIn NCBI on GitHub NCBI RSS feed Connect with NLM NLM on X (formerly known as Twitter) NLM on Facebook NLM on YouTube National Library of Medicine 8600 Rockville Pike Bethesda, MD 20894 Web Policies FOIA HHS Vulnerability Disclosure Help Accessibility Careers NLM NIH HHS USA.gov Back to Top