Patient and Endoscopic Characteristics of Postcolonoscopy Colon Cancer-A Case-control Study

Colonoscopy is imperfect for colorectal cancer (CRC) prevention. Postcolonoscopy CRC (PCCRC) is defined as CRC detected after a screening or surveillance colonoscopy. PCCRCs can be divided into noninterval CRC and interval CRC. We performed a case-control study to identify risk factors for PCCRCs and to compare risks between noninterval and interval PCCRCs.

We designed a retrospective case-control study. Using a Vermont tumor registry data set, we identified all PCCRCs diagnosed at our medical center from January 2012 to September 2017. Cases were matched 1:3 with controls of the same age, sex, and index colonoscopy date.

Fifty-four PCCRCs were matched with 162 controls and divided into noninterval (N = 27) and interval (N = 27) subsets. Overall PCCRC risk and noninterval PCCRC risk were significantly associated with history of polyps (odds ratio [OR] PCCRC = 2.71, OR noninterval = 4.41), sessile serrated polyps (OR PCCRC = 3.94, OR noninterval = 5.79), and high-risk adenoma (HRA) (OR PCCRC = 6.58, OR noninterval = 16.46) and with the index colonoscopy having a large polyp (OR PCCRC = 4.45, OR noninterval = 10.46) or having an HRA (OR PCCRC = 3.68, OR noninterval = 8.04). PCCRC risk and interval PCCRC risk were significantly associated with follow-up recommendations that did not correlate with American Gastroenterological Association surveillance guidelines (OR PCCRC = 3.30, OR interval = 4.85). Approximately 30% of PCCRCs could be attributed to endoscopic quality.

Overall PCCRC risk and noninterval PCCRC risk were significantly associated with traditional CRC risk factors including precancerous polyps and HRA on the index colonoscopy. Interval PCCRC was not associated with these risk factors. Many PCCRCs can be attributed to endoscopic quality, and nonadherence to CRC surveillance guidelines may be a novel risk factor.