Abstract Background Increasing incidence rates of colorectal cancer (CRC) diagnosed before age 50 have been reported in Canada and other Western countries. Several organizations have lowered their recommended starting age for CRC screening. We aimed to analyze CRC rates in Canada and model the impacts of lowering the age to start faecal immunochemical test (FIT) -based screening in Canada. Methods We evaluated the differences in absolute and relative incidence rates between age groups over time using the Canadian Cancer Registry data. Additionally, we used the OncoSim-Colorectal microsimulation model to examine starting FIT screening at 45 years of age over a lifetime time horizon. We estimated changes in CRC cases, deaths, potential years of life gained, and costs. Results Absolute CRC incidence increased among groups below 50 years of age, with recent birth cohorts experiencing the greatest relative increases. Microsimulation results suggest that screening at 45 would result in fewer CRC cases (15 070) and CRC deaths (6100) in Canada between 2025 and 2071. For every additional 100 colonoscopies, 3. 5 fewer CRC cases and 1. 4 fewer CRC deaths are expected. Modelling suggests this may lead to an overall cost savings of 233 million CAD over the lifespan of eligible cohorts. Conclusion Our results indicate that as CRC incidence in younger age groups has continued to increase, lowering the age to start FIT screening to 45 would result in overall population benefit through reduced CRC incidence and mortality. However, given resource considerations, provincial decision makers must evaluate changes in their programs to ensure proper implementation.
Rabeneck et al. (2026) studied this question.