Does Side Really Matter? Survival Analysis among Patients with Right- Versus Left-Sided Colon Cancer: A Propensity Score-Adjusted Analysis.

Background: Right- and left-sided colon cancer are increasingly regarded as two independent disease entities based on different gene expression profiles as well as underlying genetic mutations. Data regarding prognosis and survival are heterogeneous and more favorable in cases of left-sided colon cancer.

Objective: The purpose of this study was to evaluate the long-term oncological outcome for patients with left-sided versus right-sided stage I-III colon cancer.

Methods: Overall, 318 consecutive patients who underwent surgery for right- or left-sided sided colon cancer between 2001 and 2014 were analyzed. Analysis was performed applying a prospectively maintained database with respect to overall, disease-specific, and relative survival, using Cox regression and propensity score analyses.

Results: A total of 155 patients (48.7%) presented with right-sided colon cancer and 163 patients (51.3%) presented with left-sided colon cancer. In risk-adjusted Cox regression analysis, tumor location had no significant impact on overall survival (hazard ratio [HR] 1.53, 95% confidence interval [CI] 0.80-2.92; p = 0.197), disease-specific survival (HR 1.36, 95% CI 0.76-2.44; p = 0.301), and relative survival (HR 1.70, 95% CI 0.89-3.27; p = 0.107). After propensity score matching, the results from risk-adjusted Cox regression analysis were confirmed. Stratified by American Joint Committee on Cancer stage, patients with right-sided stage II colon cancer had a statistically significant superior relative survival compared with patents with left-sided colon cancer.

Conclusions: No significant negative impact on overall, disease-specific, or relative survival could be observed in patients with right- versus left-sided colon cancer after risk adjustment, using multivariable Cox regression and propensity score analyses.