Postoperative Radiation Therapy for Incompletely Resected Stage I NSCLC: An Analysis of the National Cancer Database

Abstract

The use of post-operative radiation therapy (PORT) in incompletely resected early stage non-small cell lung cancer (NSCLC) is controversial. This study evaluates survival outcomes after PORT in incompletely resected Stage I NSCLC, using a large national patient registry. Patients diagnosed with pathologic Stage I NSCLC treated definitively by surgery with positive surgical margins (microscopic, macroscopic, or not otherwise specified residual tumor) were identified in the National Cancer Database (NCDB). Patients receiving PORT dose ≥45 Gy were included in the analysis. Survival rates were estimated using Kaplan-Meier analysis. Univariate and multivariate Cox regression models were used to identify factors with significant impact on survival. Between 2004 and 2012, a total of 1,915 Stage I NSCLC patients were identified who met study criteria, with 388 (20.3%) receiving PORT. The percentage of patients receiving PORT did not change significantly over the study period, ranging each year between 15.8-24.7%. With median follow-up of 35.2 months, median survival was 51.6 months for all patients. Median survival for patients receiving PORT was 46.4 months, compared to 55.3 months for patients receiving surgery alone (p=0.11). On multivariate analysis, adjusting for age, gender, race, insurance status, Charlson comorbidity score, T stage, and receipt of adjuvant chemotherapy, PORT was associated with worse survival compared to no PORT (HR 1.18; 95% CI, 1.02-1.37; p=0.027). Compared to surgery alone, adjuvant chemotherapy was associated with improved survival on multivariate analysis (HR 0.61; 95% CI, 0.49-0.75; p<0.0001), whereas receipt of both PORT and chemotherapy was not associated with a statistically significant difference in survival vs. surgery alone (HR 0.93; 95% CI, 0.74-1.18; p=0.56). In this large national patient registry, PORT was offered in 20% of incompletely resected Stage I NSCLC. Addition of PORT was associated with worse survival compared to surgery alone, whereas adjuvant chemotherapy was associated with improved survival.