Prevalence, distribution, and risk factor for colonic neoplasia in 1133 subjects aged 40-49 undergoing screening colonoscopy.

Background and Aim Colorectal cancer (CRC) incidence is rising among <50-year olds. The objective of this study was to determine screening colonoscopy outcomes among 40- to 49-year olds, which are currently limited. Methods Asymptomatic 40- to 49-year olds underwent one time CRC screening colonoscopy at The Chinese University of Hong Kong between 2007 and 2011. Screening outcomes, including prevalence, distribution, and predictive factors for overall and specifically proximal colorectal neoplasia were determined. Results Among 1133 ethnic Chinese, colorectal neoplasia prevalence was 20.5%. In men, distal adenomas were associated with proximal colorectal neoplasia. Men, advancing age, a first degree relative (FDR) with CRC, and diabetes mellitus were independently associated with colorectal neoplasia. A colorectal neoplasia was three times more likely to be found in a 45- to 49-year-old man with FDR of CRC compared with a 40- to 44-year-old woman without a FDR of CRC. The numbers needed to screen one colorectal neoplasia, and one advanced neoplasm in the highest risk group of 45- to 49-year-old men with FDR with CRC were 2.8 (95% CI: 2.2-4.4) and 18.5 (95% CI: 8.9-39.2), respectively. Conclusions Colorectal neoplasia prevalence in this 40- to 49-year-old Chinese cohort was higher than previous studies. Men, advancing age, FDR with CRC, and diabetes mellitus, can be used to risk stratify for neoplasia development. Men 45-49 years old with FDR with CRC represented the highest risk subgroup, with the lowest number needed to screen. [ABSTRACT FROM AUTHOR]