The role of adjuvant chemotherapy in stage II and III mucinous colon cancer

Introduction Mucinous adenocarcinoma is a subtype of colonic adenocarcinoma associated with worse survival compared to nonmucinous adenocarcinoma. Prior studies on the effect of chemotherapy on survival in mucinous adenocarcinoma have shown mixed results. The aim of this study is to evaluate the effect of chemotherapy on the survival of patients with stage II and III mucinous adenocarcinoma. Methods The National Cancer Database was used to identify patients diagnosed with stage II or III nonmucinous adenocarcinoma or mucinous adenocarcinoma between 2004 and 2016. The primary outcome was overall survival. Results Fourteen thousand and three hundred patients with stage II mucinous colon adenocarcinoma and 16 741 patients with stage III mucinous colon adenocarcinoma were identified. There was no significant difference in survival between nonmucinous adenocarcinoma and mucinous adenocarcinoma patients in adjusted analysis for stage II disease (HR:1.00, 95%CI:0.98-1.02, P = .99), but there was a significant difference for stage III disease (HR:1.05, 95%CI:1.03-1.07, P < .001). In propensity-matched cohorts of patients with mucinous adenocarcinoma, chemotherapy was significantly associated with survival in stage II (HR:0.79, 95%CI:0.69-0.90, P < .001) and stage III disease (HR:0.56, 95%CI:0.52-0.60, P < .001). Conclusions Patients with stage II or stage III mucinous adenocarcinoma of the colon who are given adjuvant chemotherapy have significantly improved survival compared to patients not given chemotherapy.