Comparison of Number Versus Ratio of Positive Lymph Nodes in the Assessment of Lymph Node Status in Extrahepatic Cholangiocarcinoma

Background This study aimed to compare the utility of the number of positive lymph nodes with the lymph node ratio (LNR) in predicting survival after resection of extrahepatic cholangiocarcinoma. Methods A retrospective analysis of 142 consecutive patients who underwent radical resection of extrahepatic cholangiocarcinoma was performed. A total of 3066 regional lymph nodes were resected. The median number of nodes per patient was 21. The optimal cutoff values for the number of positive nodes and the LNR were determined using the Chi square scores calculated by the Cox proportional hazards regression model. Results Nodal disease was found in 59 patients (42 %). In the subsequent analysis of the impact that nodal status has on survival, 18 patients with R1/2 resection and 6 patients with paraaortic nodal disease who did not survive for more than 5 years after resection were excluded. The optimal cutoff value for the number of positive nodes was 1, and the optimal cutoff value for the LNR was 5 %. Univariate analysis identified both the number of positive nodes (0, 1, or ≥2; P = 0.005) and the LNR (0, 0–5, or >5 %; P = 0.007) as significant prognostic factors. Multivariate analysis identified the number of positive nodes but not the LNR as an independent prognostic factor ( P = 0.012). The 5-year survival rates were 64 % for the patients with no positive nodes, 46 % for the patients with one positive node, and 28 % for the patients with two or more positive nodes. Conclusions The number of positive lymph nodes predicts survival better than the LNR after resection of extrahepatic cholangiocarcinoma, provided that nodal evaluation is sufficient.