Dosimetric and clinical outcomes of stereotactic body radiotherapy for primary lung cancer: isocenter-based vs. volume-based prescription

Introduction Stereotactic body radiotherapy (SBRT) has emerged as the standard treatment modality for patients with medically inoperable early-stage non-small cell lung cancer (NSCLC). However, the optimal dose prescription method for SBRT remains controversial, with traditional isocenter-based prescriptions increasingly being replaced by volume-based prescriptions in clinical practice. Methods We retrospectively analyzed 88 consecutive patients with T1–T2aN0M0 NSCLC who were treated with SBRT between 2015 and 2024 at our institution. Patients were categorized based on prescription method, and their dosimetric and clinical outcomes were compared. Results Dosimetric evaluation results were significantly superior with volume-based prescriptions, demonstrating improved planning target volume (PTV) coverage (95% volume), and higher minimum, mean, and maximum doses ( p < 0.01 for each). Furthermore, volume-based planning reduced lung radiation exposure, indicated by lower mean lung dose and reduced irradiated lung volumes (>10–40 Gy, p < 0.01). Clinically, three-year overall survival and local control rates were markedly higher in the volume-based group than the isocenter-based group (95.0% vs. 64.0%, p = 0.01; 93.0% vs. 72.0%, p = 0.025). The incidence of Grade 2–5 radiation pneumonitis remained comparable between groups (7.1% vs. 6.5%, p = 0.617). Conclusion Volume-based SBRT prescriptions enhance both dosimetric quality and clinical efficacy without increasing pulmonary toxicity. Our results highlight volume-based prescription as a preferred strategy for SBRT in patients with early-stage NSCLC.