The standard of care for patients with brain metastases has been radiation of the entire brain. The rationale for this is that while one or several nodules of cancer are seen, in fact, microscopic cells may be present but radiographically invisible elsewhere in the brain. Radiosurgery is pencil-thin radiation beams directed from thousands of different angles to attack tumors anywhere in the brain. The radiation dose to the normal brain is reduced to an inconsequential amount whereas at the point of convergence of all the beams a huge radiation dose is administered. This is the basis of stereotactic radiosurgery.
Brain metastases are an excellent target for radiosurgery.
They are usually spherical, have blood supply from the periphery and are often resistant to standard therapy. It is estimated fifty percent of patients with brain metastases may die with uncontrolled disease in the brain using standard techniques. If the metastases cannot be contained or eliminated, damage to the normal brain may occur often with dire consequences. Stereotactic radiosurgery is perfect to boost radiation dose to brain metastases. The goal is to protect the patient's brain and neurologic function which should maintain or improve quality of life and prolong the length.