This scoping review synthesised contemporary evidence on early-onset colorectal cancer (EOCRC, ≤50 years) across 46 observational studies from 22 countries. EOCRC showed higher prevalence of MSI/dMMR tumours (6.0–33.3%) and lower BRAF V600E (2.0–10.0%) than late-onset disease, with limited evidence of CMS1 and CTNNB1 enrichment. Survival differences were heterogeneous across study populations, but stage at presentation was the consistent predictor; advanced-stage disease carried worse outcomes regardless of age group.
Why it is interesting: Refines understanding of whether early-onset colorectal cancer is a distinct biological entity or mainly a detection problem; molecular differences exist but heterogeneous survival suggests stage and healthcare access matter more than age-related biology.