High-dose fraction radiation therapy for intracranial metastases of malignant melanoma: a comparison with low-dose fraction therapy.

Malignant melanoma is considered unresponsive to conventional radiation therapy when it is delivered at a daily dose rate of 130--300 rad/fraction. Previous studies have suggested that this is in part due to a large shoulder on the radiation survival curve and that higher dose fractions might be beneficial. High-dose fraction therapy is effective for local control of cutaneous, lymph node, and soft-tissue metastases. Results in 46 patients treated with high- or low-dose fractions for intracranial metastases over the last decade in the Melanoma Unit and Department of Radiotherapy at Yale have been examined. Twenty-six patients received high-dose fraction therapy, generally 600 rad/fraction/week to 2400--3600 rad; 20 patients received low-dose fraction radiotherapy with 125--400 rad/fraction daily. All patients were given steroids, and most received chemotherapy. Results in both groups were similar. Comparison of high- and low-dose fraction patients revealed: improvement in 38 and 35%, respectively, stability in 23 and 25%, and deterioration in 38 and 40%. Median survival was three months in the high-dose fraction group and 2 1/2 months in the low-dose fraction group. Presence of hepatic metastases had no significant influence upon median survival in patients who received high-dose fraction radiotherapy. In patients receiving low-dose fraction, survival was 2 1/4 months with and three months without hepatic metastases. Death in most patients resulted from progression of central nervous system disease. Side effects, especially headache, were more prominent in the high-dose fraction group. However, in no instance did side effects require discontinuation of therapy. The greater ease of delivery for weekly high-dose fraction radiotherapy outweighed any other difference between the regimens.