Comparison in the development of colorectal cancer after screening colonoscopy between elderly and younger population

Background and aims This study aimed to evaluate and compare the incidence of colorectal cancer (CRC) in elderly participants aged >= 75 years and those Methods This retrospective cohort study was conducted at the Center for Preventive Medicine at St. Luke's International Hospital in Japan. All participants who underwent screening colonoscopy between 2005 and 2015 were included and followed up until 2020. Our primary outcome was the identification of CRC as confirmed by pathology after screening colonoscopy. We compared the development of CRC between the two groups using survival analyses. A sub-analysis to evaluate the incidence of CRC among participants with and without neoplastic polyp resection at initial colonoscopy was also performed. Results A total of 8350 participants were enrolled; the median follow-up period was 2982 days (interquartile range:1932-4141), mean age was 52.5 years (SD: 11.5) and 5274 (61.3%) participants were men. The incidence of CRC during the follow-up period was 82 (0.95%) among all participants and 11 (4.31%) among the elderly participants. Elderly participants showed a significantly higher incidence of CRC than the other group [hazard ratio, 2.56; 95% confidence interval (CI), 1.14-5.75]. The sub-analysis showed that out of 2878 participants with a neoplastic polyp at the initial colonoscopy, 52 (1.81%) developed CRC (hazard ratio, 2.85; 95% CI, 1.16-6.98). Conclusions A repeat colonoscopy might be warranted in people with high activities of daily living and few comorbidities, especially if there is a history of neoplastic polypectomy at the first colonoscopy.