Volumetric modulated arc radiosurgery for brain metastases from breast cancer: A single-center study

BACKGROUND: Whole-brain radiation therapy (WBRT) and stereotactic radiosurgery (SRS) are two treatment modalities commonly utilized to treat brain metastases (BMs). AIM: The purpose of this study is to analyse retrospectively the local control and survival of patients with BMs of breast cancer (BC) treated via radiosurgery using Volumetric Modulated Arc Therapy (VMAT-RS). METHODS: 18 patients with 41 BMs of BC and treated by VMAT-RS were studied. They were classified according to the molecular subtype of BC and the modified breast graded prognostic assessment -GPA- index. Patients presented 1-4 BMs, which were treated with 5 non-coplanar VMAT arcs. The spatial distribution of BMs, the influence of receptor status on the location of the lesions and survival assessed via the Kaplan-Meier model were analyzed. RESULTS: The median survival time (MST) was 19.7 months. Statistically significant differences were determined in the MST according to the Karnofsky performance status (p= 0.02) and the HER2 status (p= 0.004), being more prolonged in the HER2+ patients. Finally, our results showed that the cerebellum is the predominant site of breast cancer BMs, and also suggested that HER2+BMs had a predilection for some structures of the posterior circulation, such as the cerebellum, brainstem and occipital lobes (p= 0.048). CONCLUSIONS: The VMAT-RS is a technique with an overall survival comparable to other radiosurgery techniques. The baseline situation at the time of treatment, the modified breast-GPA and the molecular subtypes, are factors that significantly influence patient survival.