Efficacy and safety of risk-adapted modified stereotactic body radiotherapy for lung tumors: a single-institution retrospective study

This study evaluated the clinical outcomes and safety of risk-adapted stereotactic body radiotherapy (SBRT) using non-standard fractionation schedules for lung tumors adjacent to organs at risk (OARs). We retrospectively analyzed 81 consecutive patients (92 lesions, 2008-25) who received SBRT, including repeat irradiation outside prior fields, with non-standard regimens (56 Gy/7 fractions [fr], 50 Gy/10 fr, 60 Gy/10 fr, 48 Gy/6 fr and 35 Gy/5 fr). Endpoints included overall survival (OS), cancer-specific survival (CSS), progression-free survival (PFS), locoregional progression-free survival, local control (LC) and Grade ≥ 3 adverse events. At a median follow-up of 22.2 months (IQR, 12.1-42.9), the median OS was 26.4 months (95% CI: 17.2-43.0), with 1- and 3-year OS rates of 78.6% and 44.1%, respectively. The median PFS was 14.5 months (95% CI: 9.4-21.1), and the median CSS was 43.7 months (95% CI, 22.7-64.4). Median LC was not reached. No significant survival disparities were identified between primary and metastatic cohorts. Grade ≥ 3 toxicities occurred in 10 patients (12.3%), including two Grade 5 events. The 3-year cumulative incidence of Grade ≥ 3 toxicity in ultracentral tumors was 12.6%, with no significant differences among groups. In conclusion, risk-adapted SBRT with increased fractionation demonstrated encouraging LC while maintaining an acceptable toxicity profile for central and ultracentral lung tumors. However, the risk of severe toxicity remains, requiring careful patient selection and optimized OAR dose constraints.