Objective: To assess the impact of primary tumor side on the outcomes of non-metastatic colon cancer patients included in two clinical trials.
Methods: Overall and disease-free survivals were assessed according to the side of the tumor, through Kaplan-Meier analysis. Univariate and Multivariate analysis of predictors of disease-free survival was performed through Cox regression analysis.
Results: Kaplan-Meier analysis of disease-free survival according to the side of the primary tumor was conducted. In the overall cohort, the right-sided disease has longer disease-free survival compared to left-sided disease (p = 0.005). When the analysis was repeated among different treatment strata (observation, adjuvant 5FU/LCV, adjuvant edrecolomab), right-sided colon cancer has longer disease-free survival among observation-treated patients only (p = 0.020). Multivariate analysis was conducted among the three subsets of adjuvant treatment. The left side of the primary tumor was predictive of worse disease-free survival in patients treated with observation only (p = 0.005) but not in patients treated with adjuvant 5FU/LCV (p = 0.345) or patients treated with adjuvant edrecolomab (p = 0.661).
Conclusion: Stage II right-sided colon cancer patients have better disease-free survival compared to stage II left-sided colon cancer patients when treated with surgery only. This survival difference disappears if patients were treated with adjuvant fluoropyrimidines.
Keywords: Tumor side; adjuvant treatment; colon cancer; survival.