Gamma knife radiosurgery in the treatment of patients with single and multiple brain metastases from carcinoma of the breast

PURPOSE The purpose of the study was to evaluate the results of gamma knife radiosu rgery for treatment of brain metastases from carcinoma of the breast. MATERIALS AND METHODS From December 1993 to July 1998, 68 women with breast carcinoma metastatic to the brain were treated with gamma knife radiosurgery at Miami Neuroscien ce Center in Coral Gables, Florida The ages ranged from 25 to 80 years, wit h a median age of 52 years. Thirty-eight patients had previously received c onventional modalities of treatment for brain metastases including whole-br ain irradiation. A total of 110 treatments were given to the 68 women to an average of eight tumor sites per patient. Minimum doses ranged from 6 to 2 5 Gy to the 35% to 85% isodose line, with 35% of the prescribed minimum dos es ranging from 15 to 24 Gy Patients were treated for one to three lesions (n = 26), four to seven lesions (n = 18), and eight or more lesions (n = 24 ). RESULTS The median overall actuarial survival for the entire group was 7.8 months. The actuarial survival was 32% at 1 year. The median follow-up was 7.8 mont hs. Overall local control by lesion mas 94% (485/518 lesions), and average tumor volume tvas 3.3 cm(3). Twenty-seven (40%) of 68 eligible patients sur vived 1 year, nine (13%) survived 2 years, and two (3%) survived more than 3 years. Fifty-one of 56 documented deaths (91%) were unrelated to brain me tastases, In a subgroup of 15 patients with single brain metastases, the av erage tumor volume nas 16.6 cm(3), and local control was 73% (11/15 lesions ). The 15 patients who died had a median survival of 7.7 months (range, 3 t o 45.7 months). CONCLUSIONS Gamma knife radiosurgical treatment of patients with brain metastases from carcinoma of the breast has shifted the question of survival to that of sys temic control. There was no radiation-induced dementia, and a remarkably to w incidence of local failure was seen. Survival has been found to be indepe ndent of the number of lesions treated.