Young-onset colorectal cancer

In the past decades the incidence of colorectal cancer (CRC) in people under the age of 50 years has increased, which is referred to as early-onset CRC or young-onset CRC (YO-CRC). YO-CRC is expected to account for 11% of colon cancers and 23% of rectal cancers by 2030. This trend is observed in different parts of the world and in both men and women. In 20% of patients with YO-CRC, a hereditary cancer syndrome is found as the underlying cause; however, in the majority of patients no genetic predisposition is present. Beginning in the 1950s, major changes in lifestyle such as antibiotic use, low physical activity and obesity have affected the gut microbiome and may be an important factor in YO-CRC development. Owing to a lack of screening, patients with YO-CRC are often diagnosed with advanced-stage disease. Long-term treatment-related complications should be taken into account in these younger patients, making the more traditional sequential approaches of drug therapy not always the most appropriate option. To better understand the underlying mechanism and define relationships between environmental factors and YO-CRC development, long-term prospective studies are needed with lifestyle data collected from childhood. Young-onset colorectal cancer occurs in individuals younger than 50 years and is increasing in incidence worldwide. This Primer provides an overview of the epidemiology, diagnosis, screening, prevention, pathophysiology and management of this cancer and its impact on patient quality of life.

Automated summary

In the past decades, the incidence of early-onset colorectal cancer (CRC) or young-onset CRC (YO-CRC) has increased globally in both men and women. About 20% of YO-CRC patients have a hereditary cancer syndrome, while most cases have no genetic predisposition. Lifestyle changes such as antibiotic use, low physical activity, and obesity since the 1950s have been suggested as important factors in YO-CRC development by affecting the gut microbiome. Long-term prospective studies with childhood lifestyle data are needed to better understand the underlying mechanisms and relationships between environmental factors and YO-CRC.