Gamma Knife Radiosurgery for the Management of Greater than 15 Cerebral Metastases.

BACKGROUND: The number of metastases that can be treated safely and effectively with Gamma Knife® stereotactic radiosurgery (GKSRS) remains controversial despite continuing evidence to support its expanded utilization. We endeavored to elucidate the survival outcomes for patients who presented with ≥15 brain metastases at the time of initial SRS.

METHODS: This retrospective analysis reviewed patients treated for ≥15 brain metastases originating from breast cancer, lung cancer, or melanoma. Ninety-three patients met the inclusion criteria. In this study 3,016 tumors were treated. The median number of tumors at the first SRS procedure was 23(15-67) for breast cancer, 21(15-48) for lung cancer, and 21(15-67) for melanoma. The mean aggregate metastases volume was 8.75m3 for breast, 6.89cm3 for lung, and 9.98cm3 for melanoma.

RESULTS: Patients with breast cancer, lung cancer, and melanoma had a median survival after diagnosis of brain metastases of 18.0, 9.4, and 6.3 months, respectively. The survival after SRS was 16 months for breast cancer, 4.6 months in lung cancer and 3.1 months for melanoma. Breast cancer patients had significantly longer survival than lung cancer and melanoma patients after SRS(p=0.001). A higher Karnofsky performance score (KPS) was associated with an increase in survival across all tumor types. Repeat SRS for local or distant progression was performed in 56% of breast cancer, 35% of lung cancer, and 24% of melanoma patients.

CONCLUSION: Stereotactic radiosurgery is an effective means of managing extensive brain metastases, particularly in breast cancer patients. The primary tumor type, systemic disease and performance status heavily influence survival outcomes.