Stereotactic Body Radiation Therapy for Salvage Treatment of Recurrent Non-Small Cell Lung Cancer

Purpose: This study analyzes the outcomes and toxicity of stereotactic body radiation therapy (SBRT) as salvage treatment for recurrent non-small cell lung cancer (NSCLC). Methods and Materials: 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 positron emission tomography and computed tomography imaging at 2- to 3-month intervals. Key outcomes were presented with the Kaplan–Meier method. Results: Forty patients with 52 treatments were included at a mean of 11.82 months after treatment with EBRT (n = 21), SBRT (n = 15), surgical resection (n = 9), and SBRT after EBRT (n = 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 gross tumor volume and planning target volume were 10.80 and 26.25 cm³, 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 progression-free survival (PFS) was 14.11 months. Patients presenting after previous SBRT had improved local control (P =.021), and the same result was obtained including patients with SBRT after EBRT (P =.0037). Treatments after surgical resection trended toward worse local control (P =.061). Patients with BED ≥80 Gy had improved local PFS (P =.032), PFS (P =.021), time without any treatment failure (P =.033), and time to local failure (P =.041). Using the Kaplan–Meier method, BED ≥80 Gy was predictive of improved local PFS (P =.01) and PFS (P <.005). Toxicity consisted of 10 instances of grade <3 toxicity (16%) and no grade ≥3 toxicity. 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 a BED of ≥80 Gy.