Stereotactic Radiosurgery: Treatment of Brain Metastasis Without Interruption of Systemic Therapy.

PURPOSE: To evaluate the prevalence, outcomes, and toxicities of concurrent delivery of systemic therapy with stereotactic radiosurgery (SRS) for treatment of brain metastases. METHODS AND MATERIALS: We conducted a retrospective review of 193 patients treated at our institution with SRS without prior whole-brain radiation therapy (WBRT) for brain metastases between 2009 and 2014. Outcome metrics included administration of concurrent systemic therapy, myelosuppression, neurotoxicity, and survival. RESULTS: One hundred ninety-three patients with a median age of 61 years underwent a total of 291 SRS treatments. Thirty-seven percent of SRS treatments were delivered concurrently with systemic therapy, of which 46% were with conventional myelosuppressive chemotherapy, and 54% with targeted and immune therapy agents. Myelosuppression was minimal after treatment with both systemic therapy and SRS, with 14% grade 3-4 toxicity for lymphopenia and 4-9% for leukopenia, neutropenia, anemia, and thrombocytopenia. Neurotoxicity was also minimal after combined therapy, with no grade 4 and <5% grade 3 toxicity, 34% dexamethasone requirement, and 4% radiation necrosis, all similar to treatments with SRS alone. Median overall survival was similar after SRS alone (14.4 months) versus SRS with systemic therapy (12.9 months). In patients with a new diagnosis of primary cancer with brain metastasis, early treatment with concurrent systemic therapy and SRS correlated with improved survival versus SRS alone (41.6 vs 21.5 months, P<.05). CONCLUSIONS: Systemic therapy can be safely given concurrently with SRS for brain metastases: our results suggest minimal myelosuppression and neurotoxicity. Concurrent therapy is an attractive option for patients who have both intracranial and extracranial metastatic disease and may be particularly beneficial in patients with a new diagnosis of primary cancer with brain metastasis.