Combining FITs and HRFQ with colonoscopy improve the cost-effectiveness of a 9-year mass colorectal cancer screening program

Colorectal cancer (CRC) incidence has been increasing. Colonoscopy is still a gold standard method for its early diagnosis but using colonoscopy alone as a mass screening method is unrealistic. This study is to investigate whether combining fecal immunochemical test (FIT) and high-risk-factors questionnaire (HRFQ) with colonoscopy improve the cost-effectiveness of a mass CRC screening. CRC screening protocol combining FITs and HRFQ in the first stage and colonoscopy in the second stage was used in 50 villages/towns in 2007-2015. Residents aged 40-74 years were eligible for this free screening. A total of 160 210 (76.12%) participants completed first-stage screening, and 28 679 (17.90%) participants were defined as positive, among which 21 715 (75.72%) participants completed colonoscopy and were included in the final analysis. Outcomes were followed up until 2020. The compliance was 76.12% and 75.72% in the first and second screening stage, respectively. A total of 252 CRC, 4033 adenoma, 1234 advanced neoplasm, and 5534 total neoplasm cases were detected in the screening. The positive predictive values of CRC, adenoma, advanced neoplasm, and total neoplasm were higher in FITs+ than those in the HRFQ+ population, respectively. A total of 64.60% and 43.42% total neoplasm cases were found in FITs+ and HRFQ+ (8.02% for both), respectively. The total colorectal neoplasm and CRC cases detected by combining HRFQ and FITs increased by 55.08% and 40.00%, respectively, and their increases were higher compared to HRFQ. The detection cost per any neoplasm by combining HRFQ and FITs was