The case for radiosurgery for brainstem metastases

To challenge the prevalent pessimism regarding the outcome of patients with metastases in the brainstem resulting in the use of whole brain radiation for palliation rather than stereotactic radiosurgery for definitive control and preservation of quality of life. We present our single institution review of the efficacy and safety of treating brainstem metastases aggressively with GKRS.

Forty-one patients with 45 total lesions treated with GKRS were included. Mean age was 58.7 years, ranging from 22 to 82. Tumor volumes were objectively calculated, treatment effects assessed on imaging and clinical data collected and correlated to the radiosurgical response.

Mean survival after diagnosis of BSM was 11.6 months, ranging from 1.4 to 58.8 months. Margin dose ranged from 12 to 20 Gy. At first follow up, 11 (27%) patients had complete resolution of the treated lesion. At the second follow up 15 (37%) and third follow up 19 (46%) patients had a complete response. On average, there was a 64% decrease in tumor size at first follow up after treatment. 25 (61%) patients received WBRT in addition to radiosurgery; 16 (39%) received radiosurgery alone. There was no difference in overall survival between the two groups (p = 0.1324). ARE was seen in one patient who received  16 Gy to the margin of a 2.06 cm³ pontine tumor, but without correlative symptoms. One patient was treated with Bevacizumab^® for progressive, but asymptomatic, edema following treatment that was not controlled by corticosteroids.

Location in brainstem should not be a deterrent to the use of radiosurgery for these patients. The addition or exclusion of WBRT should be based on the clinical progression of the patient and within the limits of this study does not seem to impact overall survival. With improved survival as a result of better systemic therapy, these patients can benefit from better preservation of cognitive function by this strategy.