When Should Colon Cancer Screening Begin? The Impact of Early-Onset Colorectal Cancer and the Reality of an Unscreened Older Population.

backgroundRecent increases in colorectal cancer (CRC) incidence and mortality under age 50 have led the US to recommend starting screening at age 45 years instead of 50. Several other countries are now also reconsidering the age to start CRC screening.

aimsTo aid decision makers in making an informed decision about lowering the starting age of CRC screening in their jurisdictions.

methodsIn this article, we present the clinical and modeling evidence for the optimal age to start CRC screening and provide a checklist of considerations for decisions on age to start CRC screening.

resultsTwo observational studies showed that detection of advanced neoplasia in those aged 45-49 years undergoing colonoscopy was at least as high as in those aged 50-54 years. One Taiwanese study reported a 22% reduction in CRC incidence and a 39% reduction in CRC mortality from FIT screening in those 40-49 years compared to those 50 years and older. Nine modeling studies concluded that lowering the age to start screening to age 45 was cost-effective. However, lowering the start age can have negative spill-off effects, such as increased wait times for diagnostic colonoscopy for symptomatic individuals and decreased screening participation. In an effort to support decision making and prevent negative spill-off, the National Colorectal Cancer Screening Network in Canada proposed a Worksheet to determine the resource impact of earlier screening initiation.

conclusionsLowering the age to start CRC screening to 45 years likely leads to a reduction in CRC incidence and mortality but requires additional healthcare resources. Policy makers can use the worksheet to assess the expected increase and assess the feasibility within their jurisdictions.