Hypofractionated stereotactic radiotherapy for brain metastases from lung cancer : Evaluation of indications and predictors of local control.

Abstract

To evaluate the efficacy and toxicity of hypofractionated stereotactic radiotherapy (HSRT) for brain metastases (BMs) from lung cancer, and to explore prognostic factors associated with local control (LC) and indication. We evaluated patients who were treated with linac-based HSRT for BMs from lung cancer. Lesions treated with stereotactic radiosurgery (SRS) in the same patients during the same periods were analysed and compared with HSRT in terms of LC or toxicity. There were 53patients with 214lesions selected for this analysis (HSRT: 76lesions, SRS: 138lesions). For HSRT, the median prescribed dose was 35Gy in 5fractions. The 1‑year LC rate was 83.6% in HSRT; on multivariate analysis, a planning target volume (PTV) of <4cm(3), biologically effective dose (BED10) of ≥51Gy, and adenocarcinoma were significantly associated with better LC. Moreover, in PTVs ≥4cm(3), there was a significant difference in LC between BED10 <51Gy and ≥51Gy (p= 0.024). On the other hand, in PTVs <4cm(3), both HSRT and SRS had good LC with no significant difference (p= 0.195). Radiation necrosis emerged in 5of 76lesions (6.6%) treated with HSRT and 21of 138 (15.2%) lesions treated with SRS (p= 0.064). Linac-based HSRT was safe and effective for BMs from lung cancer, and hence might be particularly useful in or near an eloquent area. PTV, BED10, and pathological type were significant prognostic factors. Furthermore, in BMs ≥4cm(3), a dose of BED ≥51Gy should be considered.