Mo1675 RISK OF COLORECTAL CANCER FOR FECAL IMMUNOCHEMISTRY TEST (FIT)-POSITIVE PATIENTS WHO PREVIOUSLY UNDERWENT COLONOSCOPY

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Colonoscopy is recommended for fecal immunochemistry test (FIT)-positive patients; however, the risk of colorectal cancer (CRC) has not been well examined in FIT-positive patients who previously underwent colonoscopy. To investigate the risk of advanced neoplasia (tubular adenoma ≥10 mm, adenoma with a villous histology, high-grade dysplasia, and invasive cancer) for FIT-positive patients who previously underwent colonoscopy. This is a single-center, retrospective observational study. Consecutive patients who underwent colonoscopy because of a positive FIT from April 2010 to March 2017 at our hospital were included in this study. Patients were divided into three groups as follows: (1) those who experienced their first colonoscopy (initial examination group), (2) colonoscopy experience within the past 5 years, and (3) colonoscopy experience more than 5 years prior. We investigated the prevalence of advanced neoplasia among the three groups, and odds ratios that were adjusted for age, sex, and family history of colorectal cancer in the first-degree relatives, were calculated using multiple logistic regression analysis. Among 22,251 colonoscopies within the study period, 4,108 colonoscopies were performed because of a positive FIT result. We excluded the following colonoscopies; multiple colonoscopies for the same patients in the study period (n = 495), those who underwent colonoscopy within 6 months (n = 67), unknown history of colonoscopy (n = 674), and patients under 40 years old (n = 157). Finally, 2,715 patients were included in this study. Among FIT-positive patients with colonoscopy experience within the past 5 years (n = 552) and more than 5 years prior (n = 369), there were patients of 42.4% and 27.1% who had been treated for adenomatous lesions, respectively. Detection rates of invasive cancer and advanced neoplasia in all subjects were 4.2% and 12.3%, respectively. The detection rates of invasive cancer in the initial examination group, the group of history of colonoscopy within 5 years, and the group of history of colonoscopy more than 5 years prior, were 6.1% (109/1,794), 0.2% (1/552), and 1.1% (4/369), respectively. The detection rates of advanced neoplasia in each group were 15.4% (276/1,794), 5.4% (30/552), and 7.3% (27/369), respectively. Compared with the initial examination group, the odds ratio of invasive cancer in the colonoscopy within 5 years group and more than 5 years prior group were 0.05 (95% confidence interval [CI]: 0.01 - 0.19) and 0.13 (95% CI: 0.05 - 0.36), respectively, using multivariate analysis. Similarly, the odds ratios of advanced neoplasia were 0.27 (95% CI: 0.18-0.40) and 0.35 (95% CI: 0.23-0.53), respectively. The risk of CRC was low, even if the participants who previously underwent colonoscopy, especially within 5 years, were detected positive for FIT.