Long-term outcomes and genetic mutation patterns in early-onset colorectal cancer

Objective This study aimed to evaluate long-term outcomes and mutation patterns in early-onset colorectal cancer (EOCRC) patients. Methods A retrospective study was conducted on 67 colorectal cancer (CRC) patients under 40 years old. Patients were stratified by tumor location, disease stage, and genetic mutation status. Comparative analysis assessed their characteristics and clinical outcomes. Results Among EOCRC cases, 94 % were sporadic. The male-to-female distribution was nearly equal, with tumors predominantly localized in the left colon. The mean interval from symptom onset to diagnosis was 2.5 months. A majority (68.7 %) were diagnosed at an advanced stage (III–IV). Notably, left-sided colorectal cancer (LCC) had a significantly higher prevalence of advanced-stage disease than right-sided colorectal cancer (RCC) (p = 0.012). However, prognosis did not significantly differ by tumor location. Overall survival (OS) and disease-free survival (DFS) were 49 months (95 % CI, 45–54) and 48 months (95 % CI, 43–53), respectively. Germline mutations were identified in 17.9 % of cases, with over half occurring in Lynch syndrome (LS)-associated genes. Somatic mutations were found in 94 % of cases, with TP53, APC, and KRAS being the most frequently mutated genes (65.7 %, 38.8 %, and 35.8 %, respectively). No significant association was observed between these mutations and OS, and disease stage remained the only independent prognostic factor. Conclusion The majority of EOCRC cases are sporadic, with prognosis appearing independent of tumor location. The mean OS and DFS were 49 months and 48 months, respectively. No significant prognostic impact was observed for individual somatic mutations in TP53, APC, or KRAS.