Three- Versus Five-Fraction Regimens of Stereotactic Body Radiotherapy for Peripheral Early-Stage Non–Small-Cell Lung Cancer: A Two-Institution Propensity Score–Matched Analysis

We compared the outcomes of 3- versus 5-fraction stereotactic body radiotherapy regimens for early-stage non–small-cell lung cancer. Analysis was performed on 192 eligible lesions and a propensity score–matched 94 lesion subgroup. There were no statistically significant differences in outcomes between regimens, and both regimens are reasonable treatment options. Purpose: To evaluate differences in outcomes of early-stage peripheral non–small-cell lung cancer (NSCLC) treated with either 3- or 5-fraction stereotactic body radiotherapy (SBRT) at 2 institutions. Patients and Methods: Patients diagnosed with peripherally located early-stage NSCLC who received either a median dose of 60 Gy (interquartile range [IQR], 60-60, biologically effective dose, 151-151) in 3 fractions or a median dose of 50 Gy (IQR, 50-50, biologically effective dose, 94-94) in 5 fractions were included in this study. All data were retrospectively collected and reviewed in an institutional review board–approved database. Results: A total of 192 lesions in 192 patients were identified: 94 received 3-fraction SBRT and 98 received 5-fraction SBRT. Patients in the 5-fraction cohort had significantly smaller tumors (P =.0021). Larger tumor size was associated with worse overall survival (hazard ratio, 1.40, P =.0013) for all patients. A single grade 3 toxicity was reported in each cohort. A propensity score–matched cohort of 94 patients was constructed with a median follow-up of 29.3 months (IQR, 17.3-44.6) for the 3-fraction cohort and 31.0 months (IQR, 17.0-48.5) for the 5-fraction cohort (P =.84). There were no statistically significant differences between these 2 cohorts in overall survival (P =.33), progression-free survival (P =.40), local failure (P =.86), and nodal or distant failure (P =.57) at 2 years. Conclusion: The 3- and 5-fraction SBRT regimens for early-stage peripheral NSCLC had comparable clinical outcomes. Both regimens were well tolerated. A large tumor size was an adverse prognostic factor for worse survival.