Treatment strategy for metastatic brain tumors from renal cell carcinoma: selection of gamma knife surgery or craniotomy for control of growth and peritumoral edema.

We retrospectively studied the efficacy of gamma knife surgery (GKS) for metastatic brain tumors from renal cell carcinoma (RCC). To evaluate the efficacy of GKS for control of peritumoral edema, we retrospectively studied 280 consecutive metastatic brain tumors (100 from lung cancers, 100 from breast cancers, and 80 from RCC) associated with peritumoral edema. In addition, this study included 11 patients with metastatic brain tumors from RCC who underwent direct surgery. The tumor growth control rate of GKS was 84.3%. The extent of edema of RCC metastases was significantly larger than those from lung and breast cancer. Primary site (renal or not renal) and delivered marginal dose (25 Gy or more) were significantly correlated with control of peritumoral edema. All tumors treated by direct surgery were more than 2 cm in maximum diameter. Peritumoral edema at surgery was extensive but disappeared within 1-3 months, and neurological symptoms also improved in many cases. Total removal of brain metastases from RCC was easy with little bleeding in most cases. Our results suggest that GKS is effective for growth control of metastatic brain tumors from RCC. Higher marginal dose such as 25 Gy or more is desirable to obtain peritumoral edema control, so GKS is not suitable for control of symptomatic peritumoral edema associated with relatively large tumors. Tumor removal of RCC metastases is relatively easy and rapidly reduces peritumoral edema. Treatment strategy for metastatic brain tumors from RCC depends on tumor size, number of tumors, and presence of symptomatic peritumoral edema.