Predictors of Nodal and Metastatic Failure in Early Stage Non-Small Cell Lung Cancer after Stereotactic Body Radiation Therapy

Abstract Introduction/Background Many patients with early stage non–small-cell lung cancer (ES-NSCLC) undergoing stereotactic body radiation therapy (SBRT) develop metastases, which is associated with poor outcomes. We sought to identify factors predictive of metastases after lung SBRT and created a risk stratification tool. Materials and Methods We included 363 patients with ES-NSCLC who received SBRT; the median follow-up was 5.8 years. The following patient and tumor factors were retrospectively analyzed for their association with metastases (defined as nodal and/or distant failure): gender; age; lobe involved; centrality; previous NSCLC; smoking status; gross tumor volume (GTV); T-stage; histology; dose; minimum, maximum, and mean GTV dose; and parenchymal lung failure. A metastasis risk-score linear-model using beta coefficients from a multivariate Cox model was built. Results A total of 111 (27.3%) of 406 lesions metastasized. GTV and dose were significantly associated with metastases on univariate and multivariate Cox proportional hazards modeling (P  Conclusion GTV and radiation dose are associated with time to metastasis and may be used to identify patients at higher risk of metastasis after lung SBRT.