Hypofractionated stereotactic radiotherapy for the treatment of brain metastases

This retrospective review evaluated the efficacy and toxicity profiles of various dose fractionations using hypofractionated stereotactic radiotherapy (HSRT) in the treatment of brain metastases.

Between 2004 and 2007, 36 patients with 66 brain metastases were treated with HSRT. Nine of these subjects were excluded because of the absence of post-treatment magnetic resonance imaging scans, resulting in 27 patients with a total of 52 lesions. Of these 52 lesions, 45 lesions were treated with whole-brain radiotherapy plus a HSRT boost and 7 lesions were treated with HSRT as the primary treatment. The median prescribed dose was 25 grays (Gy) (range, 20 Gy-36 Gy) with a median of 5 fractions (range, 4 fractions-6 fractions) to a median 85% isodose line (range, 50%-100%). The median follow-up interval was 6.6 months (range, 0.9 months-26.8 months).

The median overall survival time was 10.8 months, and 66.7% of patients died of disease progression. After HSRT treatment of 52 brain lesions, 13 lesions demonstrated complete responses, 12 lesions demonstrated partial responses, 22 lesions demonstrated stable disease, and 5 lesions demonstrated progressive disease. Actuarial local tumor control rates at 6 months and 1 year were 93.9% and 68.2%, respectively. Maximum tumor dimension, concurrent chemotherapy, and a tumor volume <1 cc were found to be statistically significant factors for local tumor control. One patient had a grade 3 toxicity (according to National Cancer Institute Common Terminology Criteria for Adverse Events).

HSRT provides a high level of tumor control with minimal toxicity comparable to single-fraction stereotactic radiosurgery (SRS). The results of the current study warrant a prospective randomized study comparing single-fraction SRS with HSRT in this patient population.