Clinicopathological Features and Survival Outcomes of Colorectal Cancer Patients Under 40 Years: A 20-Years Single-Center Experience

In recent years, there has been a significant increase in the number of patients diagnosed with colorectal cancer (CRC) under the age of 40. Patients in this age group are diagnosed at more advanced stages, and their disease prognosis is more aggressive. We aim to present the clinicopathologic features, treatment options, and survival outcomes of patients diagnosed with CRC under 40 in our clinic and compare our data with the literature. Our study, designed with a retrospective approach, focused on patients younger than 40 with CRC diagnosed by histopathologic examination between 2004 and 2024. At diagnosis, 5% of patients were Stage 1, 25% Stage 2, 37% Stage 3, and 31% Stage 4. 41.9% of the tumors were located in the rectum, and 26.3% in the sigmoid colon. 24.8% of patients had a family history of colorectal cancer, 23.7% of patients had mucinous subtype, 12.1% had MSH/I features and 55.6% were KRAS/NRAS mutant. Among metastatic patients, oxaliplatin-based and irinotecan-based first-line therapies showed no significant difference in PFS (8.9 vs. 9.7 months, p= 0.627) and OS (34.5 vs. 32.2 months, p= 0.690). Patients are usually diagnosed at an advanced stage, which leads to an aggressive course of the disease and makes clinical management difficult. Screening programs should not be interrupted in terms of early diagnosis, especially in individuals with a family history. Furthermore, in the future, defining the molecular profile underlying the early development of sporadic CRC will help to plan individualized screening recommendations and improve management. Keywords: Colorectal cancer, Young-onset colorectal cancer, Oxaliplatin, Irinotecan