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 radiosurgery 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 Neuroscience Center in Coral Gables, Florida. The ages ranged from 25 to 80 years, with a median age of 52 years. Thirty-eight patients had previously received conventional modalities of treatment for brain metastases including whole-brain 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 25 Gy to the 35% to 85% isodose line, with 95% of the prescribed minimum doses 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 months. Overall local control by lesion was 94% (485/518 lesions), and average tumor volume was 3.3 cm3. Twenty-seven (40%) of 68 eligible patients survived 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 metastases. In a subgroup of 15 patients with single brain metastases, the average tumor volume was 16.6 cm3, and local control was 73% (11/15 lesions). The 15 patients who died had a median survival of 7.7 months (range, 3 to 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 systemic control. There was no radiation-induced dementia, and a remarkably low incidence of local failure was seen. Survival has been found to be independent of the number of lesions treated.