The treatment of brain metastases from malignant melanoma

Metastasis to the CNS develops in nearly half of patients with advanced melanoma; in 15% to 20% of these patients, the CNS is the first site of relapse. While systemic therapy for metastatic melanoma produces objective responses in 15% to 50% of patients, the available drugs do not penetrate well into the CNS, and these patients rarely benefit from systemic therapy. Although brain metastasis may be treated with surgery and/or stereotactic radiosurgery (SRS) when disease is limited to approximately one to three lesions, treatment for patients with large or multiple metastases is limited to whole brain irradiation (WBRT). While formal response and survival analyses of the impact of WBRT in melanoma have not been reported, the estimated median survival time for unselected patients with CNS metastases is only 2 to 4 months, with 1-year survival rates of less than 13%. In a selected population of patients with limited CNS involvement, surgical resection alone or in combination with WBRT appears to prolong median survival. More recently, SRS has been shown to be an effective local treatment for selected patients with brain metastases. In several retrospective reports of patients with melanoma CNS metastases, treatment with surgical resection alone or in combination with WBRT has been demonstrated to prolong median survival. More recently, SRS has been shown to be an effective local treatment for selected patients with brain metastases. In several retrospective reports, patients with CNS metastases from melanoma treated with a combination of WBRT plus SRS or SRS alone had median survivals and rates of control in the CNS superior to published reports for traditional WBRT. Most of these patients died from progressive extracranial disease with locally controlled CNS disease. Investigation of the contribution of newer systemic agents to the control of melanoma metastatic to the CNS has been based on the identification of drugs that have antitumor activity and the ability to cross the blood-brain barrier. Fotemustine is a nitrosourea that produced similar activity in CNS metastasis as in systemic disease, with a response rate of about 25%. Temozolomide (TMZ) is an oral alkylating agent that acts via the same mechanism as dacarbazine (DTIC), the most active single agent in melanoma. TMZ, which is highly active in brain tumors, has also been associated with activity in systemic and CNS metastases in melanoma patients, also in the 25% range. Efforts are underway to assess the additive benefit of TMZ and other drugs to WBRT or focused radiotherapy in this disease.