Outcomes of stereotactic body radiotherapy for large lung lesions: Is tumor size still a limiting factor?

Abstract

Objective: Evidence regarding stereotactic body radiotherapy (SBRT) for large lung lesions remains limited because most prospective trials excluded tumors ≥5 cm owing to concerns regarding treatment-related adverse events (AEs). We evaluated the efficacy and safety of SBRT in patients with large (≥4 cm) primary lung lesions. Materials and Methods: We retrospectively analyzed 29 consecutive patients with lung lesions ≥4 cm who underwent SBRT between 2020 and 2024. Clinical outcomes included radiologic response per RECIST v1.1, locoregional recurrence-free survival (LRFS), distant metastasis-free survival (DMFS), overall survival (OS), recurrence patterns, and treatment-related AEs graded per CTCAE v5.0. Survival outcomes were estimated using the Kaplan–Meier method. Results: The median tumor diameter was 45 mm (range: 40–57 mm), and the median prescribed dose was 50 Gy (range: 45–60 Gy) delivered in 5 fractions (range: 4–15 fractions). Histopathological confirmation was available in 66% of patients; the remaining 34% were clinically diagnosed based on radiologic and multidisciplinary evaluation. The median biologically effective dose (BED10) was 100 Gy (range: 84–150 Gy). After a median follow-up of 32 months (range: 3–64), the objective response rate was 69%, with complete and partial responses in 7% and 62% of patients, respectively. Local recurrence occurred in 10% of patients, while regional recurrence and distant metastasis were observed in 31% and 10%, respectively. The median LRFS, DMFS, and OS were not reached. The restricted mean LRFS, DMFS, and OS were 44.5, 56.9, and 51.8 months, respectively. On univariate analysis, no clinicopathologic or treatment-related variables were significantly associated with LRFS or OS. Treatment was well tolerated, with no Grade ≥3 AE and Grade 2 AE observed in only one patient (3.5%). Conclusions: SBRT achieved favorable local tumor control with minimal AE in patients with ≥4 cm lung lesions. These findings suggest that SBRT is a safe and effective treatment strategy for carefully selected patients with large lung lesions when individualized treatment planning and adherence to organ-of-interest dose constraints are prioritized.