Comparative Analysis of Tumor Characteristics, Treatment Response, and Oncological Outcomes in Early-Onset Versus Late-Onset Colorectal Cancer: A Retrospective Cohort Study.

INTRODUCTION

Colorectal cancer is a leading cause of cancer-related mortality worldwide, with distinct clinical features observed between early-onset colorectal cancer (EOCRC, ≤50 years) and late-onset colorectal cancer (LOCRC, >50 years). Recent trends indicate an alarming rise in EOCRC incidence, underscoring the importance of understanding its unique tumor biology and clinical behavior. Therefore, the aim of this study is to compare the tumor characteristics, clinico-pathological features, and oncological outcome between EOCRC and LOCRC.

STUDY METHODOLOGY

This retrospective cohort study evaluated 162 patients with histopathologically confirmed colorectal adenocarcinoma who underwent treatment with curative intent at Sindh Institute of Urology and Transplantation, Karachi, Pakistan, between August 2018 and July 2023. Patients were stratified into EOCRC (n=78) and LOCRC (n=84) groups. Clinical data, including demographics, tumor location, histological differentiation, staging, treatment modalities, and recurrence patterns, were extracted from medical records and analyzed using chi-square tests and Kaplan-Meier survival estimates.

RESULTS

EOCRC patients more frequently presented with rectal tumors, poorly differentiated histology, and advanced stage disease at diagnosis. Although pathological staging and resection margins were comparable, the EOCRC group exhibited a significantly higher incidence of distant recurrence and lower rates of complete pathological response to neoadjuvant chemoradiotherapy. At 24 months, both disease-free and overall survival were markedly lower in EOCRC compared to LOCRC patients.

CONCLUSION

The study demonstrates that EOCRC is characterized by aggressive tumor behavior and poorer oncological outcomes. These findings support the need to revise screening strategies, such as lowering the age threshold and incorporating flexible sigmoidoscopy, to enhance early detection and improve patient prognosis.