[Participation rate and detection of colorectal neoplasms based on multi-round fecal immunochemical testing for colorectal cancer screening in the Chinese population].

Objective: To evaluate the participation rate and detection of colorectal neoplasms based on annual fecal immunochemical testing (FIT) for three consecutive years in a population-based colorectal cancer screening program in China. Methods: Based on a population-based colorectal cancer screening program conducted from May 2018 to May 2021 in 6 centers in China, 7 793 eligible participants aged 50-74 were included and offered free FIT and colonoscopy (for those who were FIT-positive on initial screening). At baseline, all participants were invited to receive FIT. In subsequent screening rounds, only FIT-positive participants who did not undergo colonoscopy or FIT-negative participants were invited to have repeated FIT screening. FIT-positive participants were recommended to undertake colonoscopy and pathological examination (if abnormalities were found during colonoscopy). An overall of three rounds of annual FIT screening were conducted. The primary outcomes of the study were the participation rate of FIT screening, the compliance rate of colonoscopy for FIT-positive participants, and the detection rate of colorectal neoplasms. Results: Among the 7 793 participants included in this study, 3 310 (42.5%) were male, with age of (60.50±6.49) years. The overall participation rates for the first, second and third round of FIT screening were 94.0%(7 327/7 793), 86.8% (6 048/6 968) and 91.3% (6 113/6 693), respectively. Overall, 7 742 out of 7 793 participants (99.3%) attended at least one round of screening, and 5 163 out of 7 793 participants (66.3%) attended all three rounds of screening. The positivity rate was significantly higher in the first (14.6%, 1 071/7 327) round compared with the second (5.6%, 3 41/6 048) and third (5.5%, 3 39/6 113) screening rounds ( P <0.001). The overall compliance rates of colonoscopy examination among FIT-positive subjects were over 70% in three rounds, which were 76.3% (817/1 071), 75.7% (258/341) and 71.7% (243/339), respectively. In a multivariate logistic regression model considering factors including sex, education background, smoking, alcohol drinking, previous colonoscopy examination, colonic polyp history and family history of colorectal cancer among first-degree relatives, gender and smoking status were related factors affecting the participation rate of FIT screening, with higher rate in males and non-smokers. In addition, logistic regression analysis also found that age was negatively correlated with the compliance rate of colonoscopy in FIT positive patients. The detection rate of advanced tumors (colorectal cancer + advanced adenoma) declined from the first round to subsequent rounds [1st round: 1.15% (90/7 793); 2nd round: 0.57% (40/6 968); and 3rd round: 0.58% (39/6 693)], however, the positive predictive value for advanced neoplasms increased round by round, and was 11.02% in the first screening round, 15.50% in the second screening round, and 16.05 % in the third screening round. In each screening round, the detection rate for advanced neoplasms was higher in men than that in women, and increased with age. Conclusions: Annual repeated FIT screening has high acceptance and satisfying detection rates in the Chinese population. To optimize and improve the effectiveness of colorectal cancer screening, multi-round repeated FIT screening should be implemented while ensuring high participation rates.