Extent of lymph node retrieval and pancreatic cancer survival: Information from a large US population database

Background: Operative therapy of pancreatic cancer is associated with poor survival because of high recurrence rates after pancreatectomy. The effect of lymph node (LN) dissection on survival continues to be debated. Methods: A pancreatic cancer data set was created through structured queries to the Surveillance, Epidemiology, and End Results 1973 to 2000 database. Stage information was created according to 6th edition American Joint Committee on Cancer tumor-node-metastasis criteria, and the effect of LN number on survival was analyzed. Results: Out of a cohort of 20,631 patients with carcinomas of the exocrine pancreas, surgical details were available for 2,787 patients. Procedures included pancreatoduodenectomies (n = 1848; 66%), radical regional pancreatectomies (n = 516; 19%), other partial resections (n = 316; 11%), and total pancreatectomies (n = 107; 4%). For 1666 of these patients with complete clinicopathologic information, the median age was 66 years (range, 22-96 years), with an equal sex ratio. The median number of total LNs examined was 7 (range, 1-52), of positive LNs was 1 (range, 0-34), and of negative LNs was 6 (range, 0-30). Multivariate survival analysis yielded these prognostic variables: number of LNs examined, number of positive LNs, tumor size, extrapancreatic extension, radiotherapy (all P < .0001), and age (P = .0009). The greatest survival differences were observed for negative LN counts of 10 to 15. Conclusions: Stage-based survival prediction of pancreatic cancer is strongly influenced by total LN counts and numbers of negative LNs obtained. Although the mechanism remains unclear and could reflect confounding factors (margin status and institutional volume), an attempt to resect and examine at least 15LNs to yield preferably between 10 and 15 negative LNs seems sensible for curative-intent pancreatectomy.