Association of Post-Operative Radiotherapy With Survival in Resected N2 Non-Small Cell Lung Cancer Patients with Chemotherapy

BackgroupThe current staging system for completely resected pathologic N2 non-small-cell lung cancer (NSCLC) treated with chemotherapy is not suitable for predicting those patients most likely to benefit or not from post-operative radiotherapy (PORT). This study aimed to construct a survival prediction model that will enable individualized predictions of the net survival difference of PORT.MethodsA total of 3094 cases between 2002 and 2014 were extracted from the Surveillance, Epidemiology, and End Results databases. Patient characteristics were included as covariates, and their association for overall survival (OS) with and witout PORT was assessed. Externally validate data of 602 patients were included from China.ResultsAge, gender, examined lymph node, positive lymph node, tumor size, extent of surgery, and visceral pleural invasion were significantly associated with OS (P < .05). The two nomograms were developed based on clinical variables to estimate an individual's net survival difference attributable to PORT. The calibration curve for OS showed great agreement between prediction by survival prediction model and actual observation. In the training cohort, the C-index for OS was 0.619 (95% CI, 0.598-0.641) in the PORT group and 0.627 (95% CI, 0.605-0.648) in the non-PORT group. We found that PORT could improve OS (HR, 0.861; P = 0.044) for patients with a positive PORT net survival difference. ConclusionsWe established a practical survival prediction model that can be used to make individualized estimate of the net survival difference of PORT and without PORT in patients with completely resected N2 NSCLC, treated with chemotherapy.