[Gamma-radiosurgery of metastatic brain tumors]

Twenty-six cases of various brain metastases were treated with Gamma-knife. Their primary sites were: lung in 13, colon in 5, breast in 2, kidney in 2, liver in 1, ovary in 1, and a malignant melanoma. The origin of one case was not verified. There were 11 single and 15 multiple metastases. In total 70 tumors were involved. Following localization with MRI and dose planning using a computer system, radiosurgery was carried out. Tumors were treated with the maximum dose between 24 and 50Gy, and with the marginal dose between 12 and 25Gy. Early follow-up results demonstrated favorable responses chiefly by tumor shrinkage, central tumor necrosis or by decreased peritumoral edema. In fact after radiosurgery, the rates of tumor shrinkage were 55.7%, 61.8% and 66.7% at 3, 6 and 9 months respectively. The tumor control rates, including regressed and stable tumors, were 98.6%, 97.1 and 85.7 at 3, 6 and 9 month intervals respectively. Meanwhile, 14 cases were neurologically improved, and another 4 showed either no perceivable change. Neurological deterioration occurred in 4 cases by progression of brain metastasis in 2 and by perifocal edema after radiosurgery. Recurrent brain metastases occurring after radiosurgery were treated with a repetition of Gamma-knife surgery in 4 cases, resulting in good tumor control. In conclusion most of the brain metastasis can be well controlled by radiosurgery for relatively long period of time.