Lowering the colorectal cancer screening age improves predicted outcomes in a microsimulation model

Aims: While most guidelines still recommend colorectal cancer (CRC) screening initiation at age 50 years in average-risk individuals, guideline-creating bodies are starting to lower the recommended age of initiation to 45 years to mitigate the trend of increasing CRC rates in younger populations. Using CRC-AIM, we modeled the impact of lowering the CRC screening initiation age, incorporating theoretical and reported adherence rates, for triennial multi-target stool DNA (mt-sDNA) or annual fecal immunochemical test (FIT) screening. Methods and Materials: Screening strategies were simulated for individuals without CRC at age 40 and screened from ages 50 to 75 or 45 to 75 years. Outcomes included CRC incidence, CRC mortality, and life-years gained (LYG) per 1000 individuals screened (compared with no screening). Models used theoretically perfect (100%) and previously reported (71% mt-sDNA; 43% FIT) adherence rates. Results: With perfect adherence, mt-sDNA and FIT resulted in 22.2 and 23.4 more predicted LYG, respectively, with screening initiation at age 45 versus 50 years; reported adherence resulted in 23.9 and 24.4 more LYG, respectively. With perfect adherence, screening initiation at age 45 versus 50 years resulted in 26.1 and 28.6 CRC cases, respectively, with mt-sDNA and 22.8 and 25.5 cases with FIT; with reported real-world adherence there were 28.5 and 31.2 cases, respectively, with mt-sDNA and 37.1 and 40.2 cases with FIT. Similar patterns were observed for CRC deaths. With screening initiation at age 45 and reported adherence, mt-sDNA averted 8.6 more CRC cases and 3.3 more deaths per 1000 individuals than FIT. Conclusions: Estimated CRC screening outcomes improved by lowering the initiation age from 50 to 45 years. Incorporating reported adherence rates yields greater benefits from triennial mt-sDNA versus annual FIT screening.