Stereotactic body radiation therapy for salvage treatment of recurrent non-small cell lung cancer.

Abstract Purpose/Objectives This study analyzes the outcomes and toxicity of stereotactic body radiation therapy (SBRT) as salvage treatment for recurrent non-small cell lung cancer (NSCLC). Materials/Methods This retrospective analysis considered patients treated with thoracic SBRT and a history of prior external beam radiation therapy (EBRT), SBRT, or surgical resection for NSCLC. Follow-up included PET and CT imaging at 2-3 month intervals. Key outcomes were presented with the Kaplan-Meier method. Results 40 patients with 52 treatments were included at a mean 11.82 months after treatment with EBRT (21), SBRT (15), surgical resection (9), and SBRT after EBRT (7). Median imaging and clinical follow-up were 13.39 and 19.01 months, respectively. SBRT delivered a median dose of 40 Gy in 4 fractions. Median biologically effective dose (BED) was 79.60 Gy. Median GTV and PTV were 10.80 and 26.25 cc, respectively. Local control was 65%, with a median time to local failure of 13.52 months. Local control was 87% after previous SBRT but only 33% after surgery. Median overall survival was 24.46 months, and median PFS was 14.11 months. Patients presenting after previous SBRT had improved local control (p=0.021), and the same result was obtained including patients with SBRT after EBRT (p=0.0037). Treatments after surgical resection trended towards worse local control (p=0.061). Patients with BED ≥ 80 Gy had improved local-progression free survival (LPFS) (p=0.032), progression free survival (PFS) (p=0.021), time without any treatment failure (p=0.033), and time to local failure (p=0.041). Using the Kaplan-Meier method, BED ≥80 Gy was predictive of improved LPFS (p=0.01) and PFS (p Conclusions Salvage treatment for recurrent NSCLC with SBRT was effective and well tolerated, particularly after initial treatment with SBRT. When possible, salvage SBRT should aim to achieve BED of ≥ 80 Gy.