A Clinicopathological Nomogram to Predict Node Metastasis in Pancreatic Ductal Adenocarcinoma

Introduction We aim to develop a nomogram that predicts the nodal status in pancreatic ductal adenocarcinoma. Methods The National Cancer Database for pancreatic ductal adenocarcinoma was used. Patients without distant metastasis who received R0 resection and had = 12 nodes retrieved were considered for the analysis. Significant predictors of N1 were concluded from a multivariate regression model and were used to establish the nomogram, which was internally validated using the 10-fold cross-validation method. Results 6,422 patients were found eligible to derive the nomogram. Overall survival of N0 vs. N1 patients was 35.15 +/- 1.45 vs. 21.82 +/- 0.44 months. The multivariate regression identified increasing age and receiving neoadjuvant radiation as favorable predictors, whereas pancreatic head cancers, lymph-vascular invasion, histologic grade, and pathologic T stage were identified as poor predictors of nodal metastasis. The bias-corrected concordance index for the nomogram was 0.756 (95% CI 0.743-0.769). Calibration was tested based on decile groups and no difference was noted between the predicted and observed N1 (p= 0.804). Youden's index identified the predicted probability of 53.40% to be the optimal cut-off for the nomogram. When applied to pancreatic ductal adenocarcinoma patients with inadequate node sampling (< 12), overall survival for predicted N0 vs. N1 based on the nomogram were 29.90 +/- 1.41 vs. 20.57 +/- 0.72 months which is comparable to those with confirmed N0 vs. N1. Conclusion Prediction of nodal status in pancreatic ductal adenocarcinoma is critical. Development of a nomogram based on available clinicopathological features of the primary tumor to predict nodal involvement in light of inadequate node dissection is feasible.