Colon Cancer in Young Adults: Trends and Their Implications

The recent rise of young individuals under age 50 with colorectal cancer (CRC) is a startling trend in need of greater focus and research. The etiology of young-onset CRC is unexplained as efforts to blame obesity or diabetes as causative factors are simplistic and inadequate.

We describe the epidemiologic shifts of CRC incidence and mortality across age groups as well as the differences in clinicopathologic, molecular, treatment, and survival characteristics between young and older patients. Novel studies of the microbiome may elucidate bacterial causes of CRC carcinogenesis in younger individuals. Moving up the colonoscopy screening to age 45 in normal-risk individuals should prove beneficial in detecting more patients with early-onset CRC. We favor the development of risk-adaptive screening decision algorithms and flexible sigmoidoscopy screening at age 40 given the predilection for left-sided primaries in this age group. More awareness and attention to young-onset CRC will be critical to improve outcomes in this patient population.