Introduction: Due to excellent systemic treatment options and the potential for long survival, the development of brain metastases poses a clinical challenge when treating patients with primary breast cancer. This study reports on the outcomes of a multicenter study using frameless stereotactic radiosurgery alone or with surgical resection.
Methods: Patients with a primary diagnosis of breast cancer who completed treatment at The University of North Carolina or Georgetown University Hospital with stereotactic radiosurgery for intracranial metastases with no prior whole brain radiation (WBRT) between 2007-2011 were retrospectively included. Patients received 1-5 fraction radiosurgery with larger tumors receiving fractionated radiosurgery. Local control (LC) was assessed by serial MRI imaging, and overall survival was calculated using the Kaplan-Meier method. Nonparametric statistical tests were employed to explore correlations within the data.
Results: 43 patients were included in the study with a median dose of 20 Gy (range, 15 - 30 Gy), which was delivered 29 times in 1 fraction, 14 times in 3 fractions, and 2 times in 2 and 5 fractions to a total of 46 brain metastases. The median follow-up was 8 months with a median overall survival of 23.4 months (SE, 6 months), and was unrelated to local control rate (p=0.346). LC was associated with single fraction radiosurgery (p=0.03), which was delivered to tumors of a smaller median diameter than those receiving fractionated radiosurgery, 1.6 cm versus 2.5 cm respectively (p=0.005). Acute toxicity in all patients was low with no Grade 2 or higher toxicities by the CTCAE v.4 criteria.
Conclusions: Frameless stereotactic radiosurgery is a safe and effective means of treating patients with breast cancer brain metastases. Single fraction radiosurgery for smaller tumors yields superior local control without additional toxicity suggesting a need for surgical debulking, aspiration, or other techniques to facilitate the use of high dose single fraction radiosurgery in these patients.
Patient Care: This research will contribute to the understanding that every unique histological subtype of brain metastasis requires its own therapeutic approach, and that radiosurgery synergizes with certain neurosurgical interventions.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the outcomes of patients with breast cancer brain metastastes treated with frameless radiosurgery, 2) Discuss the use of neurosurgical interventions that can facilitate single fraction radiosurgery and superior outcomes.