Treatment Outcomes After Higher-dose Fractionated Stereotactic Radiotherapy (FSRT) Alone for 1-4 Brain Metastases

Abstract

Background/aim: Fractionated stereotactic radiotherapy (FSRT) is increasingly used for brain metastases. We investigated higher-dose FSRT with biologically effective doses (BED) of 49.6-66.7 Gy₁₂ Patients and Methods: Eleven characteristics were evaluated for local control (LC), overall survival (OS), and freedom from radiation necrosis (RN) in 69 patients with 1-4 brain metastases. Fifty-seven patients (83%) had extracranial metastases, 23 (33%) Karnofsky performance scores (KPS) ≤70, and 21 (30%) brain metastases ≥21 mm.

Results: At 1 and 2 years, LC-rates were 81% and 63%, OS-rates 66% and 43%, and freedom from RN-rates 98% and 87%, respectively. Median time to local progression was 35 months, median survival 19 months. KPS ≥90 was associated with better OS (p=0.048). BED of 49.6-57 Gy₁₂ (vs. 63-66.7 Gy₁₂) was associated with higher rates of freedom from RN (p=0.046), not with LC (p=0.78) or OS (p=0.55).

Conclusion: Higher-dose FSRT appears feasible and effective in patients with 1-4 brain metastases. BED 63-66.7 Gy₁₂ may not improve LC and OS but may increase RN risk.

Keywords: Fractionated stereotactic radiotherapy; biologically effective dose; brain metastases; local control; overall survival; radiation necrosis.