Risk factors for colorectal cancer in a fecal immunochemical test-positive group: The National Health Insurance Service-National Health Screening Cohort

Background and Aim: Colorectal cancer (CRC) was the fourth most common cancer in Republic of Korea in 2019. It has a gradually increasing mortality rate, indicating the importance of screening for CRC. Among the various CRC screening test, fecal immunochemical test (FIT) is a simple yet most commonly used. Neverthelss, there have been only few long-term studies on subjects with FIT-positive. Therefore, in this study, we aimed to investigate the risk factors for CRC in FIT-positive patients using the National Health Insurance Service Bigdata database.Methods: Among 1 737 633 individuals with a FIT screening result for CRC in 2009, 101 143 (5.82%) were confirmed to be FIT positive. The CRC incidence over 10 years (up to 2018) of these participants was investigated using the National Cancer Registry.Results: Out of the 101 143 FIT-positive participants, 4395 (4.35%) were diagnosed with CRC. The FIT-positive patients who underwent a second round of screening showed a 5-year cumulative CRC incidence of approximately 1.25%, whereas those who did not showed an incidence of approximately 3.75%. Among the FIT-positive patients, the CRC incidence in the non-compliance group for the second round of screening was 2.8 times higher than that in the compliance group.Conclusions: In FIT-positive participants, non-compliance with the second round of screening was identified as a major risk factor for CRC development. It is necessary to establish appropriate strategies for managing risk factors for CRC in FIT-positive patients to increase the rate of compliance with the second round of CRC screening.