Modern Systemic therapies with Radiosurgery for Brain Metastases from Breast Cancer

Objective

Stereotactic radiosurgery is an established treatment for breast cancer brain metastases. However, there is limited data regarding the clinical outcomes of SRS when delivered with targeted systemic therapies. Our aim was to assess the clinical outcomes and toxicities of patients receiving modern systemic therapy concurrently with SRS in comparison to patients undergoing traditional cytotoxic chemotherapy and SRS.

Methods

Through this IRB-approved retrospective analysis, we collected the clinical outcomes of 43 patients with brain metastases from breast cancer treated with SRS in combination with modern targeted systemic therapies (delivered within 4 weeks of SRS).

Results

A total of 235 brain metastases were treated with single fraction SRS in combination with systemic therapy. Of the 235 tumors, 49 were treated with concurrent cytotoxic systemic therapy, 60 with antibody or endocrine, 41 with immunotherapy combination, 56 were not treated with concurrent systemic therapy, and 56 received other systemic therapy. In comparison to patients receiving concurrent cytotoxic chemotherapy and SRS, those receiving antibody/endocrine therapy with SRS and those receiving no systemic therapy had significantly higher rates of local treatment failure (p=0.005). Patients receiving immunotherapy concurrently with SRS had similar rates of local treatment failure compared to those undergoing cytotoxic chemotherapy (p=0.47). We found no association between the type of systemic therapy delivered with SRS and elsewhere brain failure, or radionecrosis (all p>0.2).

Conclusion

Delivery of no therapy with SRS or the delivery of antibody/endocrine therapy concurrently with SRS were both associated with significantly higher rates of local treatment failure.