【摘要】：AIM To evaluate the prognostic value of the number of retrieved lymph nodes(LNs) and other prognostic factors for patients with distal cholangiocarcinomas, and to determine the optimal retrieved LNs cut-off number.METHODS The Surveillance, Epidemiology and End Results database was used to screen for patients with distal cholangiocarcinoma. Patients with different numbers of retrieved LNs were divided into three groups by the X-tile program. X-tile from Yale University is a useful tool for outcome-based cut-point optimization. The Kaplan-Meier method and Cox regression analysis were utilized for survival analysis.RESULTS A total of 449 patients with distal cholangiocarcinoma met the inclusion criteria. The Kaplan-Meier survival analysis for all patients and for N1 patients revealed no significant differences among patients with different retrieved LN counts in terms of overall and cancerspecific survival. In patients with node-negative distal cholangiocarcinoma, patients with four to nine retrieved LNs had a significantly better overall(P = 0.026) and cancer-specific survival(P = 0.039) than others. In the subsequent multivariate analysis, the number of retrieved LNs was evaluated to be independently associated with survival. Additionally, patients with four to nine retrieved LNs had a significantly lower overall mortality risk [hazard ratio(HR) = 0.39; 95% confidence interval(CI): 0.20-0.74] and cancer causespecific mortality risk(HR = 0.32; 95%CI: 0.15-0.66) than other patients. Additionally, stratified survival analyses showed persistently better overall and cancerspecific survival when retrieving four to nine LNs in patients with any T stage of tumor, a tumor between 20 and 50 mm in diameter, or a poorly differentiated or undifferentiated tumor, and in patients who were ≤ 70-years-old. CONCLUSION The number of retrieved LNs was an important independent prognostic factor for patients with nodenegative distal cholangiocarcinoma. Additionally, patients with four to nine retrieved LNs had better overall and cancer-specific survival rates than others, but the reason and mechanism were unclear. This conclusion should be validated in future studies.