Does the Sidedness of Colon Cancer Affect Long-Term Oncological Outcomes?

Objective: Tumor location, or sidedness, affects the prognosis of colon cancer. While recent studies generally suggest better prognoses for left-sided colon cancer, some report conflicting results. This study examined the association between colon cancer sidedness and oncologic outcomes at Khon Kaen University Hospital.Material and Methods: Patients with non-metastatic adenocarcinoma of the colon (stage I-III) who received curative treatment at Khon Kaen University Hospital from January 2012 to December 2015 were included. Survival analyses according to primary tumor location (right-sided vs. left-sided) were conducted using the Kaplan-Meier method. Cox proportional hazards regression was used to calculate the adjusted hazard ratios for 5-year overall survival (OS) and 5-year disease-free survival.Results: Among the 212 patients, 126 had left-sided colon cancer, and 86 had right-sided colon cancer. Those with left-sided colon cancer had better OS in the univariate analysis (hazard ratio [HR] 0.57, 95% confidence interval [CI] 0.34-0.96, p-value=0.037), but this was not significant in the multivariate analysis (HR 0.63, 95% CI 0.36-1.09, p-value=0.11). No relationship was found between cancer-sidedness and disease-free survival (Log-rank p-value=0.83). Other factors, including gender, lymph node status, tumor staging, and grading, were non-significant, except for T4 tumor status, which significantly affected OS (HR 3.71, 95% CI 1.91-7.12, p-value<0.001) and disease-free survival (HR 4.42, 95% CI 2.26-8.65, p-value<0.001).Conclusion: The sidedness of colon cancer did not significantly affect OS and disease-free survival. However, left-sided colon cancer tended to have a better prognosis. T4 tumor status significantly affected oncologic outcomes.