BACKGROUND: While improved screening rates have contributed to an overall decrease in the incidence of colorectal cancer (CRC), the incidence of early-age-onset CRC (EAO CRC
age <
50 years) has increased. Here, we characterize the genetic alterations and tumor microenvironment (TME) for EAO and later-age-onset (LAO) CRCs to identify relevant biological differences that might point to etiologic factors. METHODS: A cohort of EAO ( CONCLUSIONS: Overall, established EAO cancers are similar to LAO cancers in mutational profile and key TME features. High VCAN and αSMA expression in adjacent normal colon indicates a presence of factors that are associated with increased intestinal subclinical inflammation. Future mechanistic studies will be conducted to better understand the importance of these findings and related processes should be prioritized as potential etiologic factors for EAO tumorigenesis.