Ultra-central Thoracic Re-irradiation Using 10-fraction Stereotactic Body Radiotherapy for Recurrent Non-small-cell Lung Cancer Tumors: Preliminary Toxicity and Efficacy Outcomes.

BACKGROUND: We report our clinical outcomes of patients with recurrent non-small-cell lung cancer (NSCLC) tumors with ultra-central (UC) location treated with hypofractionated 10-fraction stereotactic body radiotherapy (hSBRT) in the context of thoracic re-irradiation.

PATIENTS AND METHODS: This study was conducted from 2009 to 2017 on 20 patients with recurrent NSCLC from previous thoracic radiation treatment who underwent hSBRT to 21 total UC located recurrent tumors. The planning target volumes (PTVs) that overlapped with previous treatment fields (within the 50% isodose line) were included in this analysis with endpoints of overall survival, tumor control, and toxicity.

RESULTS: The median follow-up time was 17.8 months. The median total dose of hSBRT and total biologically effective dose (BED10 ) were 65 Gy and 107.25 Gy, respectively. The median time from previous treatment was 14.6 months. The 1-year overall survival, progression-free survival, and local control rates were 68%, 35%, and 83%, respectively. The median time to local progression was 13.3 months. The most common toxicity was grade 2 or above pneumonitis (35%). One patient, whose tumor was abutting the esophagus, experienced grade 3 esophagitis. Two (10%) patients died from "unlikely" treatment-related hemorrhage from local tumor progression at 10 and 24 months after hSBRT. Bronchoscopic evaluation of 1 patient suggested endobronchial tumor progression, and clear radiographic evidence of treated hilar tumor progression was documented in the second patient's case.

CONCLUSION: Despite having a high-risk population with recurrent ultra-central NSCLC tumors in the setting of re-irradiation, our results demonstrate that ablative doses of hSBRT may serve as a feasible option for these challenging cases and concur with current reported literature.