The role of radiosurgery in the treatment of malignant brain tumors.

Most studies describing the results of radiosurgery have concentrated on the definitive treatment of small, histologically benign lesions such as vascular malformations, acoustic neurinomas, and pituitary adenomas. More recently, the role of radiosurgery using the gamma knife or LINAC-based systems to treat malignant neoplasms has become better defined. Most solitary metastases, ependymomas, well-circumscribed (on imaging studies) AAs, and a few glioblastomas (and other tumors) have responded dramatically to radiosurgery. Provided that the tumor volume was small (less than or equal to 14 cm3; 30-mm diameter), radiosurgery safely has caused tumor disappearance, shrinkage, or stabilization, regardless of prior surgery, conventional fractionated irradiation, or tumor radioresistance. For patients with recurrent or persistent, small, malignant intracranial tumors, radiosurgical treatment has obviated the need for prolonged hospitalization and has eliminated the risks associated with general anesthesia and open craniotomy.