Distant brain recurrence in patients with five or more newly diagnosed brain metastases treated with focal stereotactic radiotherapy alone.

BACKGROUND: To assess the clinical outcomes in patients with greater than 4 newly diagnosed brain metastases treated with focal stereotactic radiotherapy alone.

METHODS: All patients with five or more brain metastases who received focal radiotherapy without whole brain radiation or resection were included in this retrospective analysis. Distant brain failure (DBF), overall survival (OS) and toxicity were reported.

RESULTS: Thirty-six patients met inclusion with median clinical follow-up of 6.3 months (range: 1.1, 51.4). Twenty-nine patients received stereotactic radiosurgery (SRS) to a median dose of 20 Gy (16-20), and 7 received fractionated stereotactic radiotherapy (FSRT) to a median dose of 30 Gy (25, 30) in five fractions. The median lesion number and total brain metastases volume was 6 (5, 14) and 1.55 cc (0.12, 32.96), respectively. The Kaplan-Meier estimate of DBF at six-month was 58%, and survival probability at 1 year was 49%. Twenty percent of patients experienced systemic death without CNS relapse. Eight percent experienced grade 3 toxicity with no grade 4 or 5 toxicity. Neither tumor volume nor number predicted DBF.

CONCLUSIONS: DBF, OS and treatment toxicity were similar to historical controls with fewer than five metastases treated with focal radiation. Focal stereotactic radiotherapy alone without whole brain RT is a reasonable treatment strategy for five or more brain metastases.