Radiosurgery for pituitary metastases.

Gamma knife radiosurgery (GKS) was used to treat seven patients with pituitary metastases between November 1994 and February 2003. The diagnoses were based on magnetic resonance imaging and clinical symptoms in six patients and by previous surgery in one patient. The cancer originated in the lung in five patients, and in the breast in two patients. The tumor volume was 0.2 to 9.6 cm3 (mean 4.0 cm3). The marginal dose was 10 to 14 Gy (mean 11.9 Gy) because of the close proximity to the optic apparatus. The maximum radiation dose to the optic apparatus was 8 to 10 Gy (mean 9.5 Gy). The survival period after GKS was 0.3 to 42 months (mean 11.5 months). Five patients died of systemic disease, and one patient died of unknown causes 10 days after GKS. Tumor growth was controlled in five of the six patients (83%) followed up after GKS. Tumor regrowth was seen 18 months after GKS in one patient. The clinical symptoms improved in five of the six patients (83%) followed up. GKS is effective and useful for the primary treatment of pituitary metastases with limited survival and less invasiveness compared to conventional radiation therapy.