胃腸および消化器系

抽象的な

Impact of Index Colonoscopy Achieving Disease-Free Colon and Rectum on the Detection Rates of Colorectal Cancer and Neoplasia at the Succeeding Colonoscopy in the Setting of Annual Fecal Immunochemical Testing for Colorectal Cancer Screening

Hiroaki Igarashi, Hiroko Yamashita, Kiyoshi Tsuchiya, Yuki Hanaoka, Takayuki Shimada and Masafumi Kurisaki

Objective: We conducted a retrospective cohort study to clarify the impact of an index colonoscopy achieving disease-free colon and rectum on the detection rates of colorectal cancer (CRC) and neoplasia at the succeeding colonoscopy in the annual fecal immunochemical test (FIT)-based CRC screening.

Methods: Of patients who had undergone colonoscopy after a positive FIT result, we enrolled those who had undergone index colonoscopy within the past 5 years, where all adenomas were removed or no adenoma was detected, and those who had not previously had colonoscopy. We compared the CRC and neoplasia detection rates between the two groups and evaluated the impact of adenoma removal at the index colonoscopy on the succeeding colonoscopy.

Results: In total, 718/1165 patients were enrolled. The 5-year CRC, advanced neoplasia, and total neoplasia detection rates were 4.9%, 11.2%, and 53.4% in the index colonoscopy group and 11.7%, 22.4%, and 61.4% in the no colonoscopy group, respectively. Although these three detection rates were significantly lower in the index colonoscopy group (OR = 0.39, 95% CI: 0.20–0.76, p = 0.004; OR = 0.44, 95% CI: 0.27–0.70, p < 0.001; OR = 0.72, 95% CI: 0.52–0.99, p = 0.049, respectively), these rates seemed high. Index colonoscopy subgroup analysis revealed that the total neoplasia detection rate was significantly higher in the adenoma removal subgroup than that in the no adenoma subgroup (OR = 2.77, 95% CI: 1.60–4.80, p < 0.001).

Conclusion: In the FIT-based CRC screening, non-negligible numbers of CRC and neoplasia were detected within 5 years of the previous colonoscopy, regardless of adenoma removal, although the previous colonoscopy reduced the CRC and neoplasia detection rates. This suggests that patients receiving a positive FIT result should undergo another colonoscopy despite colonoscopy experience achieving disease-free colon and rectum within the previous 5 years.