Stereotactic radiosurgical treatment in 103 patients for 153 cerebral melanoma metastases

Purpose To report on the outcome of patients with melanoma brain metastases treated with stereotactic radiosurgery (SRS). Patients and methods One hundred three patients with 153 intracranial melanoma metastases consecutively underwent Linac-based SRS between November 1991 and October 2001. The Kaplan-Meier method, univariate comparisons with log-rank test, and multivariate analyses with classification and regression tree models were performed. Calculations were based on last imaging date rather than the date of the last visit. Results Median age was 51 years (range, 18-93 years). Median Karnofsky performance status was 90. Sixty-one patients (59%) had single brain metastasis at presentation. Treatment sequence was SRS alone (61 patients), SRS + whole-brain radiotherapy (WBRT) (12 patients), and salvage SRS after WBRT (30 patients). The median tumor volume was 1.9 cm³ (range, 0.06-22.3 cm³). The median SRS minimum peripheral dose and isodose was 18 Gy (range, 10-24 Gy) and 85% (range, 60%-100%), respectively. The median follow-up was 6 months for all patients and 13 months (range, 2-46 months) for patients alive at the time of analysis. The 1-year local control (LC) for all patients treated with SRS was 49%. Among the patients treated with initial SRS alone, the 1-year LC was better for patients with tumors ≤2 cm³ than with tumors >2 cm³: 75.2% vs. 42.3% (p < 0.05). The 1-year distant brain metastasis-free survival incidence was 14.7% for the 73 patients receiving either initial SRS alone or SRS +WBRT. The initial number of brain lesions (single vs. multiple) was the only factor with a significant effect on distant brain metastasis-free survival at 1 year: 23.5% for single metastases and 0% for multiple lesions (p < 0.05). The 1-year overall survival was 25.2%. Stratification by Score Index for Radiosurgery (SIR) revealed a significant effect on survival, which was 29% at 1 year for SIR >6 and 10% for SIR ≤6 (relative hazard ratio, 2.1; p < 0.05) in classification and regression-tree multivariate analysis involving age, Karnofsky performance status, primary tumor control, tumor volume, SRS dose, SIR (>6 vs. ≤6), and systemic disease status. Conclusions Initial SRS alone was an effective treatment modality for smaller cerebral melanoma metastases, achieving a 75% incidence of 1-year LC for ≤2 cm³ single brain metastases and should be considered in patients with SIR >6. The role of WBRT in melanoma brain metastases cannot be addressed, owing to retrospective bias toward administering this treatment to patients with more aggressive disease. A prospective study is needed to assess the role of WBRT in patients with melanoma brain metastasis.