Combining Risk Factors and Faecal Immunochemical Testing in Colorectal Cancer Screening: a Randomized Controlled Trial

Colorectal Carcinoma (CRC) is the third most frequent diagnosed cancer worldwide, with 1.4 million new cases every year. In an attempt to reduce this number many countries have implemented a nationwide screening programme targeted at detecting CRC in an early phase using fecal immunochemical tests (FITs). People with an elevated level of blood in their stool are offered a colonoscopy, an invasive medical procedure where CRCs and premalignant lesions (together also referred to as advanced neoplasia) can be detected accurately. However, the current screening method using FIT is not optimal. In FIT-based CRC screening studies, 1 in 4 participants with CRC and 2 in 3 participants with advanced neoplasia receive a negative FIT result. In contrast, an estimated 1 in 2 FIT-positives have advanced neoplasia at colonoscopy. Recent studies have demonstrated that a risk model that takes into account the FIT result and other risk factors for CRC could enhance the effectiveness of a FIT-based CRC screening programme. The objective of this study is to assess the yield of advanced neoplasia in the colon and rectum of a FIT-based risk model at colonoscopy, compared to that of a FIT-only CRC screening strategy. Our hypothesis is that a risk-based model yields significantly more advanced neoplasia at colonoscopy than the FIT by itself, and that it does not affect participation rate. To assess this hypothesis, the investigators have designed a clinical trial in which the investigators randomize 23,000 asymptomatic individuals between the age of 55 and 75 years old to either risk-based screening (intervention group) or FIT-only screening (control group). The intervention group will receive a questionnaire on risk factors of CRC (e.g. smoking, family history of CRC), and a FIT. The control group will only receive the FIT. The positivity threshold of the FIT in both groups will be set at 15 micrograms haemoglobin per gram faeces. The positivity threshold of the risk-based model in th