Gamma Knife surgery for metastatic brain tumors

Area of Science:

• Neurosurgery
• Radiation Oncology
• Oncology

Background:

• Brain metastases are a common complication of systemic cancer.
• Gamma Knife surgery (GKS) is a stereotactic radiosurgery technique used to treat brain metastases.
• Comparing outcomes between institutions is crucial for standardizing treatment protocols.

Purpose of the Study:

• To compare the efficacy and outcomes of Gamma Knife surgery (GKS) for brain metastases between two institutions in Japan.
• To identify factors influencing survival and neurological outcomes in patients treated with GKS.

Main Methods:

• A retrospective analysis of 2390 patients with brain metastases treated with GKS between 1998 and 2005 at two Japanese institutions.
• Standardized GKS procedures were performed, with all visible lesions irradiated irrespective of number, using a total skull integral dose (TSID) of ≤12 J.
• No prophylactic whole-brain radiotherapy (WBRT) was administered; salvage GKS was used for new lesions.

Main Results:

• No significant differences in patient or treatment factors were observed between the two institutions.
• Lung cancer was the most frequent primary tumor (1,572 patients).
• Median survival was similar (7.7 months in Chiba vs. 7.0 months in Mito; p=0.0635). One-year neurological survival rates were also comparable (86.6% vs. 84.2%; p=0.3310). Poor prognostic factors included active extracranial disease, male sex, and low Karnofsky Performance Scale score.

Conclusions:

• Gamma Knife surgery for brain metastases, without prophylactic WBRT, is effective in preventing neurological death and maintaining brain function.
• No significant institutional differences in treatment outcomes were found.
• Careful patient selection, ensuring all lesions are irradiated within a TSID of ≤12 J, is a critical factor for successful GKS treatment.