Abstract
BACKGROUND: Whether colorectal cancer (CRC) screening with a fecal immunochemical test (FIT) reduces mortality remains unclear. In South Korea, CRC screening with a FIT for individuals aged ≥ 50 years has been part of the Korean National Cancer Screening Program (KNCSP) since 2004. The aim of this study was to evaluate the effectiveness of the KNCSP in reducing CRC-specific mortality. METHODS: We conducted a nested case-control study using cohort-based data derived from the KNCSP database. The cohort included 5,944,540 colorectal cancer-free individuals aged ≥ 50 years as of 2004. Individuals who died after CRC diagnosis were defined as cases (n = 29,992) and their sociodemographic characteristics were matched to those of the selected controls. The effects of screening exposure, frequency, and time interval on CRC-specific mortality were analyzed according to age group. Conditional logistic regression analysis was performed. RESULTS: Compared with individuals who had never been screened, those who had ever been screened showed an OR of 0.74 (95% CI, 0.71-0.76) for CRC-specific mortality. CRC-specific mortality decreased as the number of screenings increased. Similar results were observed for those aged 50-79 years; however, the results for those aged 75-79 years were not statistically significant. Moreover, those aged ≥ 80 years had the opposite results. CONCLUSIONS: CRC mass screening using FIT is effective for individuals aged 50-74 years; therefore, this study suggests that countries considering introducing national CRC screening implement FIT for those within this age range.