SCar-biopsies After Malignant Colorectal Polypectomy of Uncertain RAdicality

Rationale: colorectal polyps may harbor adenocarcinoma. Numbers are increasing due to the nationwide colorectal screening program. After endoscopic removal, rescue surgery is often performed because radicality can not be guaranteed by the pathologist. However, in 85% of surgical specimen no residual malignancy is found. Given morbidity and mortality associated with surgery a method to diagnose residual cancer is needed. Biopsies from the polypectomy site are variably used to reduce the likelihood of residual tumor at the polypectomy site under these circumstances. However, the sensitivity of such biopsies is unknown. Objective: to evaluate the sensitivity of second-look endoscopic biopsies from the polypectomy site for residual tumor. Study design: prospective cross-sectional design using a multi-center approach. Study population: patients planned for rescue surgery for the sole reason of (potentially) irradical endoscopic resection of a colorectal adenocarcinoma without poor differentiation, lymphovascular invasion or tumor budding and without other signs of dissemination. Intervention: endoscopic biopsies from the polypectomy site before operation. Main study parameters/endpoints: sensitivity of second-look biopsies from the polypectomy site for residual tumor in the resected bowel and postoperative mortality. Various other factors will be assessed that might be associated with residual cancer. Nature and extent of the burden and risks associated with participation and benefit: Depending on the situation: a): In case a tattoo needs to be done of the polypectomy site, a second endoscopy is done anyway and taking biopsies (painless) will be of no extra burden; b): In case no tattoo needs to be done a sigmoidoscopy (lesion distal to the splenic flexure) or colonoscopy (proximal to the splenic flexure) needs to be arranged for the purpose of this study. A sigmoidoscopy takes 10-20 minutes. Preparation consists of two enemas. A colonoscopy takes 20-30 minutes. Preparation consists of drinking 3 litre of MoviPrep®, both usually doe at home. Notice that the patient has recent experience with colonoscopy. If necessary, both investigations can be arranged under conscious sedation (the rule in colonoscopy), which also implies day-care admission. The risk of complications of a second endoscopy is estimated \< 1:5000. The benefit of a 2nd colonoscopy is the discovery of new polyps in 10-25% of cases.