Gamma knife surgery in brain melanomas: absence of extracranial metastases and tumor volume strongest indicators of prolonged survival.

Objective To review a series of patients who underwent Gamma Knife surgery (GKS) to identify prognostic factors for local growth control and survival. Methods During the period 1996–2006, 77 patients (42 men and 35 women) with a total of 143 metastases underwent GKS. A solitary lesion was present in 40 patients (51.9%). Results Growth control was achieved in 114 of 128 (89.1%) tumors and 59 of 70 (84.3%) patients. The median survival was 7 months (range 0–73 months) after GKS and 67 months (range 4–327 months) from the time of diagnosis. Patients with absence of extracranial disease lived longer than patients with more widespread disease—median 16 months (range 3–52 months) versus 6 months (range 0–73 months; P = 0.014). A total tumor volume of less than 5 cc was associated with longer survival ( P = 0.041). Survival was significantly longer in recursive partitioning analysis (RPA) class 1 (22 months) than RPA class 2 (7 months) and RPA class 3 (3 months; P = 0.008). Even in cases of treatment failure with tumor growth or appearance of new metastases, GKS slowed down the cerebral disease with no significant reduction in the duration of survival. Conclusions GKS for melanoma brain metastasis provides a high rate of local tumor control. Survival is longest for well-functioning patients with absence of extracranial metastases or with an intracerebral total tumor volume less than 5 cc.