Why is colorectal cancer increasing in younger age groups in the United States

Introduction: While colorectal cancer (CRC) incidence and mortality have decreased for older adults, the rates are increasing in adults younger than 50 years of age in the United States as well as globally. In response to strong epidemiologic evidence as well as sophisticated models, the American Cancer Society (ACS) has recommended screening adults for CRC starting at age 45. Understanding the factors associated with the rise of incidence in adults younger than age 50 may help to identify those adults who may be at greatest risk. Areas covered: In this review, we provide an overview of the recent literature and discuss possible explanations for the increase in CRC in young adults including obesity and other recognized CRC risk factors, delay in diagnosis of symptomatic patients (<50 years of age), and review perspectives on the current and future status of the field. Expert opinion: Currently there are little data regarding risk factors for CRC in average risk young adults who are asymptomatic. With potential endorsement of screening at 45 years of age by US Preventive Services Task Force, more data regarding clinical and molecular risk factors associated with CRC in young adults will be available.