Evolution and impact of lymph node dissection during pancreaticoduodenectomy for pancreatic cancer.

BACKGROUND: Insufficient examination of lymph nodes after pancreaticoduodenectomy can lead some pancreatic cancer patients with N1 disease to be misclassified as N0. We examined trends in lymph node dissection throughout time and investigated how these changes affect lymph node status and its prognostic value.

METHODS: The National Cancer Data Base was queried for patients with nonmetastatic pancreatic adenocarcinoma (2004-2013) who underwent classic pancreaticoduodenectomy with antrectomy. Logistic regression was performed for odds of node positivity. Kaplan-Meier curves and Cox proportional hazards models were used to assess the impact of lymph node status on overall survival for patients diagnosed during 2-year intervals from 2004-2012.

RESULTS: Median number of examined lymph nodes was 10 (interquartile range 6-15) in 2004 vs 17 (interquartile range 12-24) in 2013. Number of lymph nodes examined was a significant predictor of N1 disease (P < .0001), with a plateau at 30 nodes. N1 disease increased from 64.4% to 68.0% (P < .0001). Survival for both N1 and N0 subgroups improved. In successive multivariate models, N0 versus N1 status was consistently protective for overall survival (P < .0001), but there was no change in the magnitude of its hazard ratio over time (overall hazard ratio 0.691; 95% confidence interval 0.660-0.723).

CONCLUSION: Contemporary patients have an adequate number of nodes examined during standard pancreaticoduodenectomy. This, along with rising rates of N1 cancer detection and improved survival for both node-positive and node-negative patients, suggest more accurate classification of lymph node status. However, no increased benefit is achieved beyond 30 nodes. Overall, lymph node status remains a strong prognosticator for overall survival.