Yield of Fecal Immunochemical Test Screening for Colorectal Cancer in Adults Aged 45-49 vs 50-54 years

The rising incidence of early-onset colorectal cancer (CRC) has prompted debate over lowering screening initiation age. Our study aimed to evaluate screening yield of FIT-based CRC screening between 45-49 and 50-54 years. Conducted within a provincial CRC screening program in China, this study employed two-sample FIT screening followed by colonoscopy for positive results. Among 733,137 participants, 89,446 were aged 45-49 years and 643,691 aged 50-54 years. Participants aged 45-49 years had higher FIT positivity (10.61%) and colonoscopy completion (46.75%) than those aged 50-54 years. However, detection rates for advanced neoplasia (0.30% vs. 0.39%) and any adenoma (0.78% vs. 0.95%) were significantly lower in the younger group, with similar results observed for PPVs. Within the 45-49 year group, comparable detection rates to 50-54 year age group were observed among individuals with established risk factors, most notably among smokers, frequent alcohol drinkers, and males. Overall, adults aged 45-49 years showed higher screening participation but lower screening yield than those aged 50-54 years. These findings highlight the importance of prioritizing individuals with elevated risk profiles for CRC screening in younger populations.