Gamma knife radiosurgery for metastatic melanoma: An analysis of survival,outcome, and complications

OBJECTIVE: Although the mainstays for treatment of metastatic brain disease have been surgery and/or external beam radiation therapy, an increasing nu mber of patients ape being referred for stereotactic radiosurgery as the pr imary intervention for their intracranial pathological abnormalities. The l ack of efficacy and cognitive and behavioral consequences of whole brain ir radiation have prompted clinicians to select patients for alternative thera pies. This study analyzes the effectiveness of Leksell gamma unit therapy f or metastatic melanoma to the brain. METHODS: We present our experience with 59 Leksell gamma unit treatment ses sions in 45 consecutive patients who presented with metastatic melanoma to the brain. Five of these procedures were performed as salvage therapy for p atients who needed second radiosurgical treatment for new lesions that were remote from the previous targets and were not included in the overall anal yses. RESULTS: The population included 78% male patients. The mean patient age wa s 53 years (age range, 24-80 yr). The mean time from diagnosis of primary m elanoma to discovery of brain metastasis was 43 months (median, 27.5 mo; ra nge, 1-180 mo). At the time of diagnosis of brain disease, 35.5% of the pat ients (16 of 45 patients) had neurological symptoms, 77.7% (35 of 45 patien ts) had known visceral metastases, and 11.1% (5 of 45 patients) had seizure disorders. Eighty-six percent of the lesions (80 of 93 lesions) were corti cal, 12% (11 of 93 lesions) were cerebellar, 1% (1 of 93 lesions) were pont ine, and 1% (1 of 93 lesions) were thalamic. Fifty-seven percent of the ses sions (31 of 54 sessions) were performed for a single lesion, 24.1% (13 of 54 sessions) for two lesions, 9.2% (5 of. 54 sessions) for three lesions, 7 .4% (4 of 54 sessions) for four lesions, and 1.8% (1 of 54 sessions) for fi ve lesions. The mean treatment volume was 5.6 cc, with a mean prescription of 21.6 Gy to the 56.0% mean isodose line. The median survival time of the patients in our population, using Kaplan-Meier curves, was 43 months from t he time of diagnosis of primary melanoma (range, 3-180 mo) and 8 months (ra nge, 1-20 mo) from the time of gamma knife treatment. Complications include d seizures within 24 hours of the procedure in four patients, with transien t nausea and vomiting in three patients, transient worsening of preprocedur e paresis responsive to steroids in three patients, and increased confusion in one patient. All 45 patients were located for follow-up (mean follow-up duration, 1 yr). After gamma knife treatment, 78% of the patients (35 of 4 5 patients) experienced either improved or stable neurological symptomatolo gy before death or at the time of the latest follow-up examination. There w ere 26 deaths (58%). The cause of death was determined to be neurological i n only 2 of 45 patients (7.7%). Follow-up magnetic resonance images reveale d a 97% local tumor control rate of gamma knife-treated lesions, with 28% r adiographic disappearance (9 of 32 cases). Six patients developed new lesio ns remote from radiosurgical targets and underwent second procedures. CONCLUSION: Although metastatic melanoma to the brain continues to have a f oreboding prognosis for long-term survival, gamma knife radiosurgery seems to be a relatively safe, noninvasive, palliative therapy, halting or revers ing neurological progression in 77.8% of treated patients (35 of 45 patient s). The survival rate matches or exceeds those previously reported for surg ery and other forms of radiotherapy. Only 7.7% of the patients in our study population who died as a result of metastatic melanoma (2 of 26 patients) died as a result of neurological disease. The routine use of therapeutic le vel antiseizure medication is emphasized, considering the findings of our r eview.