Invasive Nodal Staging via Endobronchial Ultrasound and Outcome in Patients Treated with Stereotactic Body Radiation Therapy for Early-Stage Non-Small Cell Lung Cancer – Results from a Single Institution Study

Introduction Stereotactic body radiation therapy (SBRT) is an effective treatment for medically inoperable early-stage non-small cell lung cancer (NSCLC). The prognostic value of invasive nodal staging (INS) for patients undergoing SRBT has not been studied extensively. Herein, we report the impact of INS in addition to 18F-FDG-PET on treatment outcome for patients with NSCLC undergoing SBRT. Materials and Methods Patients with stage I/ II NSCLC who underwent SBRT were included with IRB approval. Clinical, dosimetric, and radiological data were obtained. Overall survival (OS), regional recurrence free survival (RRFS), local recurrence free survival (LRFS), and distant recurrence free survival (DRFS) were analyzed using Kaplan Meyer method. Univariable analysis (UVA) and multivariable analysis (MVA) were performed to assess the relationship between the variables and the outcomes. Results A total of 376 patients were included in the analysis. Median follow up was 43 months (IQ 32.6-45.8). Median OS, LRFS, RRFS, DRFS were 40, 32, 32, 33 months, respectively. The 5-year local, regional, and distant failure rates were 13.4%, 23.5 and 25.3%, respectively. The 1-year, 3-year and 5-year OS were 83.8%, 55.6%, and 36.3%, respectively. On MVA, INS was not a predictor of either improved overall or any recurrence free survival endpoints while larger tumor size, age, and adjusted Charleston co-morbidity index (aCCI) were significant for inferior LRFS, RRFS, and DRFS. Conclusion Invasive nodal staging did not improve overall or recurrence free survival among patients with early-stage NSCLC treated with SBRT whereas older age, aCCI and larger tumor size were significant predictors of LRFS, RRFS, and DRFS. Microabstract In those with early-stage non-small cell lung cancer undergoing stereotactic body radiation therapy, the prognostic significance of invasive nodal staging (INS) has not been studied well. We performed a retrospective review of 376 patients using multivariable analysis to determine correlation of INS and survival. INS was not associated with improved survival or recurrence rates. Other factors like adjusted CCI and tumor size were better predictors of recurrence.