Post-colonoscopy Colorectal Cancer in Sweden 2003-2012: Survival, Tumor Characteristics, and Risk Factors.

Rate of post-colonoscopy colorectal cancer (PCCRC) is a measure of colonoscopy quality, but there are conflicting results from studies of survival times of patients with PCCRC. We assessed survival times of patients with PCCRC and characterize microscopic and macroscopic features of post-colonoscopy colorectal tumors.We performed a population-based cohort study using data from a database in Sweden, on 458,937 colonoscopies (54.0% women patients) performed from 2003 through 2012. Rates of colorectal cancer within 3 years of a colonoscopy were calculated based on the World Endoscopy Organization guidelines. Risk factors were evaluated using Poisson regression analysis. We used Cox regression models and Kaplan-Meier analyses, stratified by sex, to assess conditional survival. Logistic regression models were used to evaluate features of post-colonoscopy colorectal tumors, including stage location (right, left, or rectum) differentiation grade (high or low), synchronous tumors, perineural growth, resection margins, and mucinous and vessel characteristics.Within 36 months after a colonoscopy, there were 19,184 individuals who had received a diagnosis of CRC; 1384 of these PCCRCs (7.2%). The proportion of individuals with PCCRC decreased from 9.4% in 2003 to 6.1% in 2012. The highest risk factors for PCCRC were prior diagnosis of CRC (relative risk [RR], 3.31; 95% CI, 2.71-4.04), ulcerative colitis (RR, 5.44; 95% CI, 4.75-6.23), Crohn's disease (RR, 3.81; 95% CI, 2.98-4.87), and prior polypectomy (RR, 2.32; 95% CI, 1.97-2.72). Individuals with PCCRCs had shorter survival times than individuals with CRCs detected during the index colonoscopy. Multivariate hazard ratios for PCCRC were 2.75 for men (95% CI, 2.21-3.42) and 2.00 for women (95% CI, 1.59-2.52), respectively. Individuals with left-side PCCRC had shorter survival times that patients with CRC detected during index colonoscopy. Post-colonoscopy colorectal tumors had increased odds of low differentiation grade (odds ratio, 1.27; 95% CI, 1.09-1.49) compared colorectal tumors detected during index colonoscopy.In analysis of colonoscopies in Sweden, the rate of PCCRCs decreased from 9.4% in 2003 to 6.1% in 2012. Diseases that require surveillance (such as prior colorectal neoplasms and inflammatory bowel diseases) are largest risk factors for PCCRC. Patients with PCCRC have shorter times of survival patients with CRC detected during their initial colonoscopy-especially women and patients with left-side tumors.

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