Abstract: Objective To analyze the effect of postoperative adjuvant chemotherapy on prognosis of patients with distal cholangiocarcinoma(DCC).Methods Clinical data of 455 DCC patients who received radical surgical treatment from 2010 to 2015 were retrospectively analyzed in SEER database.Propensity score matching(PSM) was employed to reduce the bias,Kaplan-Meier test and Log-rank test were used to evaluate prognostic differences and Cox proportional risk model was used to analyze independent prognostic risk factors.Results  After PSM,it is found that TNM stage,postoperative chemotherapy and N stage were correlated with the prognosis of DCC patients,and postoperative adjuvant chemotherapy was an independent risk factor affecting the prognosis of patients.Further subgroup analysis showed that there were no significant difference in 3 year survival rate and  median survival time of DCC patients with stage Ⅰ between the postoperative chemotherapy group and the only surgery group(P>0.05),while the prognosis of patients with stage Ⅱ in the chemotherapy group was significantly better than that in the only surgery group(P＜0.05).Postoperative chemotherapy could prolong the 3 year survival rate and median survival time of the moderately differentiated and poorly differentiated/undifferentiated patients(all P＜0.05),while there were no significant differences in the 3 year survival rate and median survival time of the highly differentiated patients in the postoperative chemotherapy group and the only surgery group(P>0.05).Adjuvant chemotherapy could benlifit the 3 year survival rate and postoperative median survival time of patients with positive lymph nodes( P＜0.05),but did not significantly improve the survival prognosis of patients with negative lymph nodes( P>0.05).Conclusion Postoperative chemotherapy is associated with long-term survival benefit of patients with distal cholangiocarcinoma,and it is an independent risk factor affecting prognosis.DCC patients with TNM stage Ⅱ,moderately differentiated and poorly differentiated/undifferentiated pathologically and lymph node positive status are potential beneficiaries of postoperative chemotherapy.

Key words: adjuvant chemotherapy, distal cholangiocarcinoma, prognosis, SEER database, propensity score matching(PSM)