Diagnostic yield of the one-year surveillance colonoscopy after curative colorectal cancer resection

PURPOSE: Guidelines recommend routine colonoscopy 1 year after curative colorectal cancer resection, despite limited evidence supporting its diagnostic yield. This study evaluated the real-world outcomes of 1-year surveillance colonoscopy following colorectal cancer resection. METHODS: This is a retrospective observational study using pathology, clinic, and endoscopy data patients who underwent segmental oncologic resection for primary colon or rectal. Adenocarcinoma between January 2007 and June 2020 in Winnipeg, Manitoba. Patients were excluded if they had a total proctocolectomy, if no follow-up colonoscopy data were available, or if the date of the first surveillance scope was < 6 months or > 24 months from surgery. Colonoscopy findings were categorized as adenocarcinoma, advanced adenoma, simple adenoma or normal. RESULTS: A total of 454 patients met the inclusion criteria. The 1-year surveillance colonoscopy detected 2 (0.44%) adenocarcinomas, 3 (0.66%) advanced adenomas, and 87 (19.2%) simple adenomas. The majority (n = 362, 79.7%) had normal colonoscopy results. Preoperative bowel preparation quality was not reported for either recurrent adenocarcinoma. Neither of the recurrent adenocarcinomas was associated with elevated carcinoembryonic antigen (CEA), abnormal imaging, or known hereditary cancer syndromes. CONCLUSIONS: Our data demonstrate a low observed rate of clinically significant findings at 1-year surveillance colonoscopy following colorectal cancer resection. Incomplete documentation of index colonoscopy quality limited assessment of whether surveillance findings represented true metachronous lesions or lesions missed at the preoperative examination. Given the low event rate and observational study design, these findings should be interpreted as descriptive real-world data regarding postoperative surveillance outcomes.