Quality of Preoperative Colonoscopy Affects Missed Postoperative Adenoma Detection in Colorectal Cancer Patients.

BACKGROUND: Despite thorough preoperative screening, 19-30% of synchronous polyps or adenomas are detected after colon cancer surgery. Remnant synchronous lesions require additional colonoscopy procedures or surgery. AIM: To investigate factors of preoperative colonoscopy potentially affecting the detection of missed lesions in patients subjected to colorectal cancer surgery. METHODS: Of 1147 colorectal cancer patients subjected to curative open or laparoscopic colectomy and colonoscopy at the Chungnam National University Hospital from January 2012 to December 2016, 518 patients underwent pre- and postoperative colonoscopy. The index colonoscopy was defined as the last preoperative endoscopy performed. We analyzed pre- and postoperative medical charts for colonoscopy and pathological data. The effects of patient, procedure, and tumor factors on the postoperative adenoma detection rate, advanced adenoma detection rate, and adenoma miss rate (AMR) were analyzed. RESULTS: The overall AMR was 25.7% (95% confidence interval, 22.2-29.8%). Comparing optimal and non-optimal bowel preparation groups, the latter had greater postoperative polyp missed rate (PMR), AMR (p < 0.01), and AAMR (p = 0.272). The optimal preparation group allowed identification of more synchronous adenomas than in the fair (OR 5.72) and poor (OR 11.39) preparation groups. On univariate analysis, patient age and left-sided colectomy (p < 0.01) influenced AMR. Multivariate analysis showed that age, preoperative bowel preparation, and left colon resection influenced postoperative AMR. CONCLUSION: A better quality of index colonoscopy had a positive effect on lowering the detection rate of postoperative adenoma. Older age and suboptimal bowel preparation at the index colonoscopy and left-sided colectomy had negative effects on lowering the postoperative AMR.