Lymph node ratio versus number of affected lymph nodes as predictors of survival for resected pancreatic adenocarcinoma.

BACKGROUND: The objective of this study was to compare the prognostic significance of the lymph node ratio (LNR) with the absolute number of affected lymph nodes for resected pancreatic ductal adenocarcinoma. METHODS: Data were collected from 84 patients who had undergone pancreatoduodenectomy for pancreatic ductal adenocarcinoma over a 10-year period. Patients were categorized into four groups according to the absolute LNR (0, 0-0.199, 0.2-0.299, > or =0.3). Kaplan-Meier and Cox proportional hazard models were used to evaluate the prognostic effect. RESULTS: An LNR of > or =0.2 (median survival 8.1 vs. 35.7 months with LNR < 0.2; p < 0.001) and > or =0.3 (median survival 5.9 vs. 29.6 months with LNR < 0.3; p < 0.001), tumor size (p < 0.017), positive resection margin (p < 0.001), and nodal involvement (p < 0.001) were found to be significant prognostic markers following univariate analysis. Following multivariate analysis, only LNR at both levels [> or =0.2 (p = 0.05; HR 1.8) and LNR of > or =0.3 (p = 0.01; HR 2.7)] were independent predictors of a poor outcome. The number of lymph nodes examined had no effect on overall survival in either node-positive patients (p = 0.339) or node-negative patients (p = 0.473). CONCLUSIONS: The LNR represents a stronger independent prognostic indicator than the absolute number of affected lymph nodes in patients with resected pancreatic ductal adenocarcinoma.