Oncologic Effects of Primary Tumor-Sidedness on Patients with Stages 1–3 Colon Cancer: A Meta-Analysis

Background Previous studies comparing the oncologic outcomes of primary tumor-sidedness for patients with colon cancer have reported a worse prognosis for those with right-sided tumors. However, most of these studies evaluated patients with metastatic disease. Methods PubMed, EMBASE, and the Cochrane Library were searched for studies that assessed the effects of primary tumor-sidedness on survival outcomes for patients with stages 1, 2, and 3 colon cancer. The hazard ratio (HR) for primary tumor location was estimated for overall survival (OS), cancer-specific survival (CSS) and disease-free survival (DFS). Results The inclusion criteria were met by 37 studies involving 581,542 patients. The patients with a right-sided tumor had better CSS (HR, 0.67; 95% confidence interval [CI], 0.56–0.80; p