Screening for Colorectal Cancer in Individuals Younger Than 50 Years

What Is the Issue? Incidence of colorectal cancer in individuals younger than 50 years in Canada is rising, despite existing recommendations in Canada advising that colorectal cancer screening be initiated at 50 years. In response to the also increasing incidence of colorectal cancer observed in other jurisdictions, screening for colorectal cancer in individuals of average risk younger than 50 years has been recommended. These factors have prompted reconsideration of current Canadian guidelines regarding the age at which colorectal cancer screening should be initiated. What Did We Do? To inform considerations about the age at which colorectal cancer screening should best be initiated, CADTH identified and summarized studies comparing colorectal cancer screening in individuals of average risk younger than 50 years with either no screening or screening in individuals of average risk aged 50 years and older. An information specialist conducted a search of peer-reviewed and grey literature sources. Recommendations from evidence-based guidelines for screening individuals of average risk younger than 50 years were also sought and summarized. What Did We Find? Data from 1 retrospective cohort study in the US conducted in a large sample across 13 years suggested there is higher incidence of colorectal cancer among individuals between the ages of 45 and 49 years who underwent screening colonoscopy than in those between the ages of 50 and 54 years. Data from a retrospective cohort study conducted in Greece with a limited sample size across 1 year of observation demonstrated no difference in the cumulative incidence of colorectal cancer in individuals of average risk younger than 50 years or 50 years and older. Estimates from 4 modelling studies (1 of which was Canadian) that investigated screening in individuals younger than 50 years indicate that life-years may be gained, colorectal cancer cases and deaths may be reduced, but that numbers of lifetime colonoscopies and complications from screening would likely increase. One economic evaluation conducted in Portugal concluded that there is no cost-utility for colorectal cancer screening in individuals of average risk younger than 50 years at a willingness-to-pay threshold of €39,760, given current estimates of incidence in this age cohort. Seven evidence-based guidelines identified recommend that colorectal cancer screening be initiated in individuals of average risk at age 45 years, whereas 1 guideline recommends against screening in individuals of average risk beginning at 45 years and 1 guideline recommends against screening beginning at age 40 years. Most evidence-based guidelines highlight the lack of empirical evidence describing clinical effectiveness and cost-effectiveness as limitations when developing recommendations. What Does It Mean? Empirical data describing the effectiveness of colorectal cancer screening in individuals of average risk younger than 50 years remain limited, although a preponderance of evidence-based guidelines identified by this review recommend in favour of doing so. Modelled data estimate that colorectal cancer screening in individuals younger than 50 years may produce benefits, although these estimates are vulnerable to model inputs and assumptions (perfect adherence to screening protocols, for instance), and may not adequately account for the potential harms of screening. Additional opportunities for maximizing the benefits of colorectal cancer screening may include targeting increased uptake among disadvantaged and high-risk groups, including those 50 years and older. Broader considerations that address societal benefit and costs — including health equity and implementation — are essential to inform decision-making concerning colorectal cancer screening in individuals of average risk younger than 50 years.

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