The Rise of Early-Onset Colorectal Cancer: Clinical Characteristics and Outcomes in a Young Patient Population

Abstract

Background: The incidence of early-onset colorectal cancer (EOCRC), defined as diagnosis at age ≤50 years, is rising globally. Despite younger age and presumed clinical fitness, EOCRC often presents at advanced stages and displays distinct biologic and treatment profiles. Methods: We conducted a retrospective cohort study of patients aged ≤50 years with histologically confirmed colorectal adenocarcinoma treated at a tertiary cancer center in Saudi Arabia from 2015 to 2021. Clinical, pathologic, molecular, and treatment data were extracted. Survival outcomes were analyzed using Kaplan–Meier methods, and prognostic factors were assessed via Cox regression models. Results: Among 97 patients (mean age 43 ± 5 years; 56% male), 34% presented with metastatic disease and 75% had left-sided or rectal tumors. Obesity was prevalent in 24% of cases. Surgical resection was performed in 79% of patients, of whom 47% received adjuvant chemotherapy. First-line systemic therapy was administered in 39%, but attrition limited progression to subsequent lines. Median overall survival (OS) was 20 months (interquartile range [IQR], 11–30). Progression-free survival (PFS) declined from 8 months in first-line to 4 months in third-line therapy. On multivariable analysis, obesity was independently associated with worse OS (hazard ratio [HR] 6.63, p = 0.035). Conclusion: Despite favorable performance status, EOCRC frequently presents with advanced disease and limited systemic therapy durability. Obesity emerged as an independent adverse prognostic factor. These findings reinforce EOCRC as a biologically distinct entity, underscoring the need for tailored screening strategies, early intensification of therapy, and molecularly guided care.