Treatment and Prognosis of Isolated Local Relapse after Stereotactic Body Radiotherapy for Clinical Stage I Non-Small-Cell Lung Cancer Importance of Salvage Surgery

Introduction: Many efforts have been made to detect local relapse (LR) in the follow-up after stereotactic body radiotherapy (SBRT) for non-small-cell lung cancer (NSCLC) although limited data are available on its treatment and prognosis. We aimed to characterize treatment options and clarify long-term outcomes of isolated LR after SBRT for patients with clinical stage I NSCLC. Methods: We reviewed our institutional database in search of patients with isolated LR after SBRT for clinical stage I NSCLC at our institution between 1999 and 2013. Patient characteristics were compared with Mann-Whitney U test, (2) test, or Fisher's exact test as appropriate. Survival outcomes were estimated with Kaplan-Meier method. Potential prognostic factors were investigated using Cox proportional hazard model. Results: Of 308 patients undergoing SBRT for clinical stage I NSCLC, 49 patients were identified to have isolated LR. Twelve patients underwent salvage surgery, none underwent radiotherapy, and eight patients received chemotherapy, whereas 29 patients received best supportive care. No patient characteristic except operability was significantly related with patient selection for LR treatments. Five-year overall survival (OS) rate of the whole cohort was 47.9% from SBRT and 25.7% from LR. Salvage surgery was associated with improved OS after LR (p = 0.014), and 5-year OS for patients undergoing salvage surgery was 79.5% from LR. Conclusions: It was confirmed that our patient selection for salvage surgery for isolated LR was associated with favorable survival outcomes. Operability based on multidisciplinary conferences, rather than measurable patient characteristics, is essential for appropriate patient selection for salvage surgery.