Willauer AN, et al. - In this retrospective review of more than 36,000 patients, researches characterized clinical and molecular traits specific to early-onset colorectal cancer (CRC) that help discriminate these patients from those 50 years old or older. They used three independent cohorts to assess baseline features according to the CRC onset age. The influence of age on the consensus molecular subtype (CMS) prevalence was determined in a fourth cohort. Microsatellite instability, synchronous metastatic disease, primary tumors in the distal colon or rectum, and fewer BRAF V600 mutations were more likely to be seen among early-onset patients vs patients 50 years old or older. Fewer adenomatous polyposis coli (APC) mutations and an increased prevalence of signet ring histology were reported in patients aged 18 to 29 years vs other patients younger than 50 years. For very young patients with CRC (18-29 years) and those with predisposing conditions, special consideration and further investigations appeared necessary. In patients younger than 40 years, a high rate of CMS1 was found.