RESULTS OF SURGICAL RESECTION FOR PROGRESSION OF BRAIN METASTASES PREVIOUSLY TREATEDBY GAMMA KNIFE RADIOSURGERY

Abstract

PURPOSE To determine treatment outcome following surgical resection for progressive brain metastases after gamma knife radiosurgery (GKR), and to explore the role of dynamic contrast agent-enhanced perfusion MR imaging and proton spectroscopic MR imaging studies (MRS/P) in predicting the pathological findings. METHODS Between 1997 and 2002, 32 patients underwent surgical resection for suspected progression of brain metastases from a cohort of 245 patients with brain metastases treated with GKR. Post radiosurgery MRI surveillance was performed at 6, 12, and then every 12 weeks after GKR. In some cases additional MRI with spectroscopy and/or perfusion (MRS/P) was used to aid differentiation of radiation change from tumor progression. The decision to perform neurosurgical resection was based on MRI and/or clinical evidence of lesion progression among patients with KPS ≥ 60 and absent or stable systemic disease. RESULTS Thirteen percent (32/245) of patients and six percent (38/611) of lesions required surgical resection after GKR. The median time from GKR to surgical resection was 8.6 months (range: 1.7–27.1). The 6, 12 and 24 month actuarial survival from time of GKR was 97%, 78, 47% for the resected patients and 65, 40, 19% for the non-resected patients (P < 0.0001). Two year survival of patients requiring two resections after GKR was 100% compared to 39% for patients undergoing one resection (P = 0.02). The median survival of resected patients was 27.2 months (range: (7.0–72.5) from the diagnosis of brain metastases, 19.9 months (range: 5.0–60.7) from GKR, and 8.9 months (range: 0.2–53.1) from surgical resection. Tumor was found in 90% of resected specimens and necrosis alone in 10%. MRS/P studies were performed in 15 resected patients. Overall, MRS/P predicted tumor in 11 lesions, confirmed pathologically in 9 lesions and necrosis alone was found in 2. The MRS/P predicted necrosis alone in 3, where pathology revealed viable tumor in 2 and necrosis in 1 lesion. CONCLUSIONS Surgical intervention of progressive brain metastases after GKR in selected cases leads to a meaningful improvement in survival. Further studies are necessary to determine the role of MRS/P in the post radiosurgery surveillance of brainmetastases.