Colorectal Cancer in the Young

Swati G. Patel, Dennis J. Ahnen

Colorectal cancer incidence has been rapidly rising in those under the age of 50 over the last 20 years. This paper will review the epidemiology, clinicopathologic, molecular features, proposed risk factors, and prevention/treatment approach for early onset CRC (EOCRC) patients. EOCRC appears to have a different spectrum of clinical, pathologic, and molecular presentation compared to CRC diagnosed in older individuals. EOCRCs are disproportionately located in the distal colon; these patients tend to present with symptoms, and there is a longer interval between symptoms and diagnosis. There may be a distinct molecular signature, including progression through the microsatellite and chromosomal stable (MACS) pathway and LINE-1 hypomethylation for a subset of EOCRCs. The majority of EOCRCs are sporadic without clear risk factors that would have made the patient eligible for earlier screening. There is an acute need for educational efforts aimed at both providers and patients to raise awareness about CRC in the young. Improving adherence to screening in young patients eligible for screening and emphasizing early evaluation of symptoms are important steps to decreasing the burden of CRC in younger patients. Modeling and empiric data are needed to determine whether our current screening approach should be modified and whether causation and treatment options may be different in a molecular subset EOCRCs.