The impact of lymph node number on survival in patients with lymph node-negative pancreatic cancer

Objectives: The role of lymph node (LN) dissection for pancreatic cancer remains uncertain, and guidelines for a minimum LN number have not been established. We hypothesized that LN number in node-negative (N0) pancreatic cancer influences survival. Methods: The Surveillance, Epidemiology, and End Results database was queried for patients undergoing resection for N0 pancreatic adenocarcinoma between 1988 and 2003. Lymph node number was categorized as 1-10, 11-20, and >20. Results: In a cohort of 1915 patients, the median LN number was 7 (range 1-57); 1365 (71%) patients had <11 LN. Survival was significantly better in the 11 to 20 compared with the 1-10 group (median, 20 vs 15 months, respectively, P < 0.0001); no difference was observed between the 11-20 and >20 groups (median, 20 vs 23 months, respectively, P = 0.14). Multivariate analysis demonstrated the prognostic significance of LN number for determining overall survival (hazard ratio 0.98, 95% confidence interval: 0.97-0.99; P < 0.0001). Conclusions: Pancreatic cancer lymphadenectomy with examination of >10 LN is associated with improved survival in N0 disease and should be considered a benchmark for adequacy of surgery and/or pathology. Currently, only a minority of patients are assessed by this measure. The variation in LN number may be indicative of diverse surgical technique and/or pathologic analysis and warrants further investigation.