Outcomes and Toxicity following 3 or More Definitive Courses of Thoracic Radiation Therapy for Non-Small Cell Lung Cancer.

Abstract

Purpose: Salvage re-irradiation is increasingly utilized to manage non-small cell lung cancer (NSCLC) locoregional recurrence or new lung primaries in previously treated areas. There is sparse information on efficacy and toxicity profile. We report a large experience of patients treated with multiple courses of definitive radiation for new and recurrent NSCLC.

Methods and materials: Medical records of patients who underwent ≥ 3 definitive thoracic radiation therapy (RT) courses for new or recurrent NSCLC at our cancer center from 2012 through 2021 were retrospectively reviewed following institutional review board approval. Toxicity was graded per Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 and outcomes were estimated using Kaplan-Meier.

Results: Among 51 patients meeting inclusion criteria, there were 161 definitive thoracic RT courses (8 received 4 courses). Of these courses, 119 (74%) entailed SBRT for localized lesions; the remaining were conventional fractionation (half included concurrent chemotherapy). Seventeen patients (33%) received SBRT for every thoracic treatment course. There was overlap of treatment fields between separate courses for 38 patients (75%). Following last thoracic RT, median overall survival (OS) was 2.9 years (range, 1.5-4.4) and progression-free survival (PFS) was 14-months (range, 8.5-19). Three-year estimated OS (±standard error) was 81% (± 10%) for patients who received SBRT for every course and 32% (± 9%) among those treated with mixed modality. Overall Grade 3 toxicity incidence was 6%, no Grade 4 or 5 events.

Conclusion: Definitive thoracic radiation can be a safe and effective local control modality (despite multiple prior treatments) and should be considered when planning multidisciplinary salvage therapy.