Radiosurgery for metastatic brain tumors.

Stereotactic radiosurgery (SRS) precisely delivers high-dose radiation to a small target (usually less than 3-4 cm in diameter), in a single session with steep dose-fall, employing various radiation methods. SRS provides good tumor control for small brain metastases from various primary cancers, with minimal untoward effects on surrounding normal brain. This excellent tumor control prevents neurological death and maintains good activity of daily life. Although surgery with whole-brain radiation therapy (WBRT) remains an important option for patients with a solitary brain metastasis, SRS with or without WBRT should be considered in patients with a limited number of small tumors and a good prognosis. Many reports, as well as both retrospective and prospective reviews, have shown WBRT before or after SRS to improve local control and reduce new distant lesion emergence. However, upfront WBRT does not improve survival. There are two major delivery techniques, Gamma Knife (GK; Elekta AB, Stockholm, Sweden) SRS and linear accelerator (LINIAC)-based SRS. They are based on quite different concepts, and have different techniques and clinical applications. These differences complicate the discussion of the limitations of and indications for SRS and the necessity for prophylactic WBRT. This review discusses numerous aspects of SRS, its value as compared with other treatment modalities, the necessity for prophylactic WBRT with SRS, the limitations of and indications for SRS, and the difference between GK and LINIAC SRS, based on the literature and our experience, and proposes a new strategy for the treatment of brain metastases in view of the available clinical data and experience.