The performance of FIT-based colorectal cancer screening: results from a population-based program

Colorectal cancer is the third leading cause of cancer-related mortality globally. Colonoscopy remains the gold-standard approach for early diagnosis; however, relying solely on colonoscopy as a mass screening method is not feasible. The aim of this study was to assess whether identifying the faecal immunochemical test positive (FIT(+)) population was a more efficient and economical option for colorectal cancer (CRC) screening. The performance of risk stratification models based on a FIT was also evaluated. This study was based on data from the Cancer Screening Program in Urban China. Among 358 primary health care units from 2020 to 2023, residents aged 45-74 years who either tested positive on the high-risk factor questionnaire (HRFQ) or had a positive FIT result were identified as high-risk participants and were subsequently recommended to undergo a free colonoscopy. The FIT(+) group was defined as those with a positive FIT result, while the FIT(-) group consisted of individuals with a negative FIT result but a positive HRFQ. The participation rates were 32.62% and 17.11% in the FIT(+) group and FIT(-) group, respectively. A total of 44 cases of CRC, 1789 cases of nonadvanced adenoma and 601 cases of advanced adenoma were detected throughout the entire screening program. The positive predictive values (PPVs) for CRC, non-advanced adenoma and advanced adenoma were greater in the FIT(+) group than in the FIT(-) group. In the overall CRC screening, the detection costs for each case of CRC, advanced neoplasm and nonadvanced adenoma were US$22,196, US$1514, and US$545, respectively. Compared with the cost in the FIT(-) group, the cost of detecting CRC cases in the FIT(+) group was reduced by nearly 80%. For advanced neoplasms or nonadvanced adenomas, the cost reduction exceeded 50%. After a median follow-up period of 2.22 years, 292 individuals received a CRC diagnosis, and the calculated incidence was greater in the FIT(+) group than in the FIT(-) group. The proportion of stage I CRC in the FIT(+) group was 40%, which was significantly greater than the percentage (15%) in the FIT(-) group. The performance of the risk stratification model that combined risk factors with the FIT result was superior to that of models relying solely on the FIT or risk factors. Colonoscopy participation and screening yield were more favourable in the FIT(+) group than in the FIT(-) group. The combination of FITs and HRFQs is an essential initial step in a large-scale CRC screening program. The association between FIT status and CRC burden should be evaluated after an extended follow-up period.