Validation of a prognostic model including the number of harvested lymph-nodes in the setting of non-small cell lung cancer patients undergoing curative resection: a multicentre analysis.

BACKGROUND The prognostic role of the extension of lymphadenectomy in Non-small-cell lung cancer is still a debated and intriguing issue. The aim of this study is to validate a prognostic score including the number of resected lymph-nodes previously reported using a large multicentre dataset. METHODS From 01/2002 to 12/2012, data on 4858 NSCLC patients undergoing curative-intent surgery in six Institutions were retrospectively reviewed. To test the discriminative ability of the model, composed of a panel of high-risk,pathologic stage, nodal status, age, number of Resected Nodes and intermediate risk factors (gender, grading, histology), was determined. The Kaplan-Meier method was used to estimate Overall(OS), Cancer-Specific(CSS) and Disease-free Survival(DFS) curves, and the log rank test was adopted to evaluate the differences between groups. RESULTS Pathological stages were: I in 46,5%, II in 24,1%, III in 27,8% and IV in 1,6% of cases. Overall, 5-years OS, CSS and DFS were 54,6%, 76,7% and 44,8%, respectively. Stratifying the sample of 3948 patients with complete data into Low-risk (LR, #107), Intermediate-risk (IR, #1268) and High-Risk (HR, #2573) groups, the optimal prognostic discrimination power of this score was confirmed (C-statistics: 0.71, 95%CI 69-73). Specifically in LR, IR and HR, 5-years OS was 83,5%, 66,4% and 46,2% (p<0.0001), 5y-CSS was 95,8%, 89% and 69% (p<0.0001), and 5y-DFS was 74,7%, 59.1% and 35,5% (p<0.0001), respectively CONCLUSIONS: Our study confirms the optimal prognostic discrimination power of the previous prognostic model including the number of harvested nodes.