Objective: To determine the optimal number of lymph nodes to examine for accurate staging of node-negative pancreatic adenocarcinoma after pancreaticoduodenectomy. Design, Setting, and Patients: Data from the National Cancer Institute's Surveillance, Epidemiology, and End Results program (1988-2002) were used to identify 3505 patients who underwent pancreaticoduodenectomy for adenocarcinoma of the pancreas, including 1150 patients who were pathologically node negative (pN0) and 584 patients with a single positive node (pN1a). Perioperative deaths were excluded. Univariate and multivariate survival analyses were performed. Main Outcome Measure: Examination of 15 lymph nodes appears to be optimal for accurate staging of node-negative adenocarcinoma of the pancreas after pancreaticoduodenectomy. Results: The number of nodes examined ranged from 1 to 54 (median, 7 examined nodes). Univariate survival analysis demonstrated that dichotomizing the pN0 cohort on 15 or more examined lymph nodes resulted in the most statistically significant survival difference (log-rank χ2=14.49). Kaplan-Meier survival curves demonstrated a median survival difference of 8 months (P < .001) in favor of the patients who had 15 or more examined nodes compared with patients with fewer than 15 examined nodes. Multivariate analysis validated that having 15 or more examined nodes was a statistically significant predictor of survival (hazard ratio, 0.63; 95% confidence interval, 0.49-0.80; P < .0001). Furthermore, a multivariate model based on the survival benefit of each additional node evaluated in the pN0 cohort demonstrated only a marginal survival benefit for analysis of more than 15 nodes. Approximately 90% of the pN1a cohort was identified with examination of 15 nodes. Conclusions: Examination of 15 lymph nodes appears to be optimal to accurately stage node-negative adenocarcinoma of the pancreas after pancreaticoduodenectomy. Furthermore, evaluation of at least 15 lymph nodes of a pancreaticoduodenectomy specimen may serve as a quality measure in the treatment of pancreatic adenocarcinoma.
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