PET/MR-imaging to Differentiate Between Responders and Non-responders Receiving Preoperative Chemotherapy

The incidence of malignity in the gastroesophageal junction (GEJ) is rising in Denmark, 400 new cases annually 1. 60% of the patients with GEJ cancer have disseminated disease (M1-stage) at time of diagnosis and are consequently unable to undergo curative intended surgery. The prognosis is poor, with 5-year survival rates of approximately 2 % for these 60% and the treatment only consists of palliative therapy 1. For the remaining approximately 40 % who are assessed as candidates for curative intended surgery, the 5-year survival rate is 33 % 1. This emphasizes the need for further research and knowledge concerning tumour biology and spontaneous course of the disease. In Denmark, all cancer patients are enrolled in a specific cancer program. The primary diagnostic work-up for GEJ cancers includes gastroscopy with biopsy, blood samples, ultrasonography scan, Positronemissionstomography (PET) and Computed tomography (CT) alone or PET/CT in combination 2. From these parameters physicians determine resectability and TNM-stage (tumour staging), which is substantial for the prognosis and future treatment. The primary goal is to achieve a macroscopically resection of tumour and lymphnodes in relation to the stomach and oesophagus (Esophagectomi a.m. Ivor Lewis and D1+ lymphadenectomy in the abdomen and thorax). In addition to surgery, patients receive perioperative chemotherapy, which consist of three series of chemotherapy preoperative and three series postoperative approximately 21-28 days after surgery. Approximately 12.6 % of patients receiving perioperative chemotherapy prior to surgery will have disease progression due to chemotherapy resistance during the therapy 3. This unintentionally leads to shifting these patients from the resectable group to non-resectable group (palliative treatment). Thus, the possibility for detecting response to perioperative chemotherapy is of great interest. A paradigm shift towards an individualised tailored therapy form has emerged in