ABSTRACT
BACKGROUND: The objective of this study was to report our institutional experience with Gamma Knife® Radiosurgery (GKRS) in the treatment of patients with brain metastases. METHODS: Retrospectively collected demographic and clinical data on 126 patients with intracranial metastases were reviewed. The patients in our study underwent GKRS at Vidant Medical Center between 2009 and 2014. Kaplan-Meier curves were used to compare survival based on clinical characteristics for univariate analysis, and a Cox proportional hazards model was used for multivariate analysis. RESULTS: The median age of the patient population was 62 years. Medicare patients constituted 51% of our patient cohort and Medicaid patients 15%. The most common tumor histologies were non-small cell lung cancer (50%), breast cancer (12.7%), and melanoma (11.9%). The median overall survival time for all patients was 5.8 months. Patients with breast cancer had the longest median survival time of 9.15 months, while patients with melanoma had the shortest median survival time of 2.86 months. On univariate analysis, the following factors were predictors for improved overall survival, ECOG score 0 or 1 vs. 2 or greater (17.0 vs. 1.8 months, p < 0.001), controlled extracranial disease vs. progressive extracranial disease (17.4 vs. 4.6 months, p = 0.0001), recursive partitioning analysis Stage I vs. II-III (18.2 vs. 6.2 months, p < 0.007), multiple GKRS treatments (p = 0.002), prior brain metastasectomy (p = 0.012), and prior chemotherapy (p = 0.021). Age, ethnicity, gender, previous external beam radiation therapy, number of brain metastases, and hemorrhagic vs. non-hemorrhagic tumors were not predictors of longer median survival time. Number of metastatic brain lesions of 1-3 vs. ≥4 (p = 0.051) and insurance status of Medicare/Medicaid vs. commercial insurance approached significance (13.7 vs. 6.8 months, p = 0.08). On multivariate analysis, ECOG performance status 0-1 (p < 0.001), multiple GKRS treatments (p = 0.003), and control of extracranial disease (p = 0.001) remained significant predictors of survival. CONCLUSION: ECOG score, control of extracranial disease, and multiple GKRS treatments are predictors of longer median survival following GKRS in our patient population. GKRS is an effective treatment for brain metastases, but these factors may be considered in patient selection for GKRS.
ABSTRACT
PURPOSE: To develop a novel conformal superficial brachytherapy (CSBT) device as a treatment option for the patient-specific radiation therapy of conditions including superficial lesions, postsurgical positive margins, Dupuytren's contractures, keloid scars, and complex anatomic sites (eyelids, nose, ears, etc.). METHODS AND MATERIALS: A preliminary CSBT device prototype was designed, built, and tested using readily available radioactive seeds. Iodine-125 (125I) seeds were independently guided to the treatment surface to conform to the target. Treatment planning was performed via BrachyVision Planning System (BPS) and dose distributions measured with Gafchromic EBT3 film. Percent depth dose curves and profiles for Praseodymium-142 (142Pr), and Strontium-90/Yttrium-90 (90Sr-90Y) were also investigated as potential sources. Results achieved with 90Sr-90Y and electron external beam radiation therapy were compared and Monte Carlo N-Particle eXtended 2.6 simulations of 142Pr seeds were validated. RESULTS: BPS was able to predict clinical dose distributions for a multiple seeds matrix. Calculated and measured doses for the 125I seed matrix were 500 cGy and 473.5 cGy at 5 mm depth, and 171.0 cGy and 201.0 cGy at 10 mm depth, respectively. Results of 90Sr-90Y tests demonstrate a more conformal dose than electron EBRT (1.6 mm compared to 4.3 mm penumbra). Measured 142Pr doses were 500 cGy at surface and 17.4 cGy at 5 mm depth. CONCLUSIONS: The CSBT device provides a highly conformal dose to small surface areas. Commercially available BPS can be used for treatment planning, and Monte Carlo simulation can be used for plans using beta-emitting sources and complex anatomies. Various radionuclides may be used in this device to suit prescription depths and treatment areas.