The side of the primary tumor affects overall survival in colon adenocarcinoma: an analysis of the national cancer database

Background Due to conflicting study results on the effect of laterality on overall survival in primary colon cancers, we sought to examine the impact of left compared to right-sided primary tumors on overall survival for stage I-III colon cancer using the largest dataset to date. Methods The 2006-2013 NCDB was queried for patients with single primary, stage I-III colon adenocarcinoma and grouped by stage and tumor location. Results For stage I-II tumors, 114,839 patients had resection (62% right:38% left). After adjustment, patients with right-sided tumors had superior survival ([HR right as reference]: 1.13, 95% CI 1.09-1.17, p < 0.001). For stage III tumors, 71,024 patients had resection, (59% right:41% left). After adjustment, patients with left-sided tumors had superior survival with chemotherapy (HR 0.85, p < 0.001) and no difference in survival without chemotherapy (HR 0.97, p = 0.18). Conclusions The side of the primary tumor impacts overall survival across stages for colon adenocarcinoma. Patients with right-sided tumors have superior survival for stage I-II disease while patients with left-sided stage III disease demonstrate a survival advantage, suggesting an opportunity for investigators to use sidedness as a surrogate for prognosis and chemoresponsiveness.