Radiosurgery for the treatment of brain metastases

Abstract

Surgical resection and whole brain radiotherapy (WBRT) have been the mainstays of the treatment of cerebral metastases. This approach results in a median survival of about 10 months. Several recent publications and our own experience suggest that a similar median survival can be achieved with stereotactic radiosurgery using either the Leksell Gamma Knife or the linear accelerator radiosurgical techniques. In addition, radiosurgery can effectively treat metastatic tumors in surgically inaccessible sites, e.g., the brainstem. Radiosurgery can also effectively treat multiple intracranial metastases in widely separated areas of the brain. In fact, we have shown that patients with multiple metastases have similar lengths and qualities of survival as do patients with single metastases treated with stereotactic radiosurgery. The most important predictor of success in radiosurgical treatment of cerebral metastases is the neurological status of the patient, usually expressed as the Karnofsky Performance Status (KPS). The histological type of primary cancer is not an outcome predictor. Even so-called "radioresistant" tumors (e.g., melanoma, renal cell) respond favorable to radiosurgery. A great benefit of radiosurgery is the virtual lack of perioperative complications and the minimal interference with quality of life compared either to surgery or to fractionated whole brain radiotherapy. Long-term complications of radiosurgery are infrequent and primarily relate to failure of local tumor control (10%) and radiation-induced edema or necrosis. The later usually can be controlled with corticosteroids, but occasionally, craniotomy may be required to treat life-threatening mass effects. We believe that radiosurgery is the treatment of choice for most cerebral metastases. Only large lesions (>3.5-4 cm diameter) and those which require immediate decompression to treat life-threatening mass effects require surgical treatment. Radiosurgery also may be used to treat residual disease after surgical resection. We have shown that WBRT does not increase the efficacy of radiosurgery in the treatment of cerebral metastases, and, therefore, we prefer to avoid both the short-and long-term morbidity of that treatment, if possible.

The role of the gamma knife in the treatment of malignant primary and metastatic brain tumors

“…The Harvard group has also confirmed this finding 31 . A recent reanalysis of our data does indicate that whole‐brain radiotherapy reduces the incidence of new brain metastases, but this reduction does not significantly affect the length or quality of survival 29 …”

“…The most common sources of brain metastases are cancers of the lung and breast, which in our experience make up about 60% of our total cases 29 . Metastases from melanomas and cancers of the colon and kidney added to metastases from the lung and breast account for more than 80% of our total cases 29 …”

Single cerebral metastasis from colorectal adenocarcinoma

“…Radiotherapic treatment is complementary to surgical therapy, while chemotherapy is completely dependent on the nature of the primitive tumor [4]. Stereotactic therapy, used in three of our patients in whom further cerebral localization of the primitive tumor developed, allows control of a high percentage of cerebral lesions (up to 90%, according to the authors' opinions) [25,26]. It is associated with a low incidence of complications when the lesions have a diameter less than 3 cm, the primitive disease is under control, and there are no further extracranial metastases [25], while the therapeutic result is not influenced by the number of lesions or age of the patients, providing they are in good general condition (KPS>60).…”

Outcomes in patients treated with gamma knife radiosurgery for brain metastases from malignant melanoma

“…[7] The tumor control rate is found to be as high as 97% [14] and is therefore not different from metastatic tumors of other origins. [17,18] When performing studies to determine the natural history of a disease or the prognosis with treatment, we are tempted to overemphasize the importance of our own findings and reject theories in conflict with our own hypotheses. To determine the ways in which our findings influence how we practice, we must ask at least the following general questions: 1) Is it reasonable to assume that the findings are reproducible and that the observed parameters did not only occur by chance?…”