Survival and outcomes in patients with ≥ 25 cumulative brain metastases treated with stereotactic radiosurgery

2021 ◽  
pp. 1-11
Keyword(s):  
Brain Metastases ◽  
Stereotactic Radiosurgery ◽  
Gamma Knife ◽  
Radiation Effects ◽  
Univariate Analysis ◽  
Survival Rates ◽  
Gamma Knife Radiosurgery ◽  
Cumulative Number ◽  
Study Results ◽  
The Mean

OBJECTIVE In the era in which more patients with greater numbers of brain metastases (BMs) are being treated with stereotactic radiosurgery (SRS) alone, it is critical to understand how patient, tumor, and treatment factors affect functional status and overall survival (OS). The authors examined the survival outcomes and dosimetry to critical structures in patients treated with Gamma Knife radiosurgery (GKRS) for ≥ 25 metastases in a single session or cumulatively over the course of their disease. METHODS A retrospective analysis was conducted at a single institution. The institution’s prospective Gamma Knife (GK) SRS registry was queried to identify patients treated with GKRS for ≥ 25 cumulative BMs between June 2013 and April 2020. Ninety-five patients were identified, and their data were used for analysis. Treatment plans for dosimetric analysis were available for 89 patients. Patient, tumor, and treatment characteristics were identified, and outcomes and OS were evaluated. RESULTS The authors identified 1132 patients with BMs in their institutional registry. Ninety-five patients were treated for ≥ 25 cumulative metastases, resulting in a total of 3596 tumors treated during 373 separate treatment sessions. The median number of SRS sessions per patient was 3 (range 1–12 SRS sessions), with nearly all patients (n = 93, 98%) having > 1 session. On univariate analysis, factors affecting OS in a statistically significant manner included histology, tumor volume, tumor number, diagnosis-specific graded prognostic assessment (DS-GPA), brain metastasis velocity (BMV), and need for subsequent whole-brain radiation therapy (WBRT). The median of the mean WB dose was 4.07 Gy (range 1.39–10.15 Gy). In the top quartile for both the highest cumulative number and highest cumulative volume of treated metastases, the median of the mean WB dose was 6.14 Gy (range 4.02–10.15 Gy). Seventy-nine patients (83%) had all treated tumors controlled at last follow-up, reflecting the high and durable control rate. Corticosteroids for tumor- or treatment-related effects were prescribed in just over one-quarter of the patients. Of the patients with radiographically proven adverse radiation effects (AREs; 15%), 4 were symptomatic. Four patients required subsequent craniotomy for hemorrhage, progression, or AREs. CONCLUSIONS In selected patients with a large number of cumulative BMs, multiple courses of SRS are feasible and safe. Together with new systemic therapies, the study results demonstrate that the achieved survival rates compare favorably to those of larger contemporary cohorts, while avoiding WBRT in the majority of patients. Therefore, along with the findings of other series, this study supports SRS as a standard practice in selected patients with larger numbers of BMs.

Gamma knife radiosurgery for renal cell carcinoma brain metastases

2002 ◽  
Vol 97 ◽  
pp. 489-493 ◽  
Author(s):  
Laura Hernandez ◽  
Lucia Zamorano ◽  
Andrew Sloan ◽  
James Fontanesi ◽  
Simon Lo ◽  
...  
Keyword(s):  
Renal Cell Carcinoma ◽  
Brain Metastases ◽  
Cell Carcinoma ◽  
Gamma Knife ◽  
Median Survival ◽  
Renal Cell ◽  
Univariate Analysis ◽  
Gamma Knife Radiosurgery ◽  
Content Type ◽  
Fine Print

Object. The purpose of this study was to clarify the effectiveness of gamma knife radiosurgery (GKS) in achieving a partial or complete remission of so-called radioresistant metastases from renal cell carcinoma (RCC) and to propose guidelines for optimal treatment Methods. During a 5-year period, 29 patients (19 male and 10 female) with 92 brain metastases from RCC underwent GKS. The median tumor volume was 4.7 cm3 (range 0.5–14.5 cm3). Fourteen patients (48%) also underwent whole-brain radiotherapy (WBRT) before GKS, and two patients (6.8%) after GKS. The mean GKS dose delivered to the 50% isodose at the tumor margin was 16.8 Gy (range 13–30 Gy). All cases were categorized according to the Recursive Partitioning Analysis (RPA) classification for brain metastases. Univariate analysis was performed to determine significant prognostic factors and survival. The overall median survival was 7 months after GKS treatment. Age, sex, Karnofsky Performance Scale score, and controlled primary disease were not predictors of survival. Combined WBRT/GKS resulted in median survival of 18, 8.5, and 5.3 months for RPA Classes I, II, and III, respectively, compared with the median survival 7.1, 4.2, and 2.3 months for patients treated with WBRT alone. Conclusions. These results suggest that WBRT combined with GKS may improve survival in patients with brain metastases from RCC. Furthermore, this improvement in survival was seen in all RPA classes.

scholarly journals MLTI-15. A CASE SERIES OF PRE-OPERATIVE GAMMA-KNIFE RADIOSURGERY FOR RESECTABLE BRAIN METASTASES

2019 ◽  
Vol 1 (Supplement_1) ◽  
pp. i17-i17
Author(s):  
Tatsuya Takezaki ◽  
Haruaki Yamamoto ◽  
Naoki Shinojima ◽  
Jun-ichiro Kuroda ◽  
Shigeo Yamashiro ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Stereotactic Radiosurgery ◽  
Gamma Knife ◽  
Systemic Treatment ◽  
Radiation Necrosis ◽  
Gamma Knife Radiosurgery ◽  
Case Series ◽  
Phase 3 ◽  
Optimal Sequence ◽  
Median Margin

Abstract Recent advances in the systemic treatment of various cancers have resulted in longer survival and higher incidence of brain metastases. Phase 3 trials in north America and in Japan have demonstrated that stereotactic radiosurgery will be a standard adjuvant modality following surgery for resectable brain metastases. However, we don’t know the optimal sequence of this combination therapy. We hypothesized that pre-operative stereotactic radiosurgery for resectable brain metastases provides favorable rates of local control, overall survival, leptomeningeal dissemination and symptomatic radiation necrosis. We have experienced 4 cases of resected brain metastases within 1–7 days after Gamma-knife surgery (median margin dose:22Gy) and have been following their clinical course. We will show the repressive cases.

scholarly journals Gamma Knife versus Frameless Linear Accelerator Based Stereotactic Radiosurgery for Brain Metastases: Clinical Outcomes and Factors Associated with Local Failure and Radiation Necrosis

2021 ◽  
Author(s):  
Gregory S. Alexander ◽  
Jill S. Remick ◽  
Emily S. Kowalski ◽  
Kai Sun ◽  
Yannick Poirer ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Stereotactic Radiosurgery ◽  
Clinical Outcomes ◽  
Gamma Knife ◽  
Linear Accelerator ◽  
Radiation Necrosis ◽  
Univariate Analysis ◽  
Local Failure ◽  
Rank Test ◽  
Chi Square Analysis

Abstract BackgroundSingle-fraction stereotactic radiosurgery (SF-SRS) for the treatment of brain metastases can be delivered with either a Gamma-Knife platform (GK-SRS) or with a frameless linear accelerator (LA-SRS) which vary based on patterns of prescribing, patient setup and radiation delivery. Whether these differences affect clinical outcomes is unknown. MethodsPatients treated for metastatic brain cancer treated with SF-SRS from 2014-2020 were retrospectively reviewed and clinical outcomes were recorded on a per lesion basis. Covariates between groups were compared using a Chi-square analysis for dichotomous variables and t-test for continuous variables. Median follow up was calculated using the reverse Kaplan Meier (KM) method. Primary endpoints of local failure (LF) and symptomatic radiation necrosis (RN) were estimated using the KM method with salvage WBRT used as a censoring event. Outcome estimates were compared using the log-rank test. Multivariate analysis (MVA) and Cox proportional hazards modeling were used for statistical analyses. Propensity score (PS) adjustments were used to reduce the effects confounding variables.ResultsOverall, 119 patients with 287 lesions were included for analysis which included 57 patients (127 lesions) treated with LA-SRS compared to 62 patients (160 lesions) treated with GK-SRS. On both multivariate and univariate analysis, there was no statistically significant differences between GK-SRS and LA-SRS for LF, RN, or the combined endpoint of either LF or RN (multivariate p-value=0.17).ConclusionsIn our retrospective cohort, we found no statistically significant differences in the incidence of RN or LF in patients treated with GK-SRS when compared to LA-SRS.Trial Registration: Retrospectively registered

scholarly journals Clinical dose profile of Gamma Knife stereotactic radiosurgery for extensive brain metastases

2020 ◽  
pp. 1-5
Author(s):  
Gregory Neil Bowden ◽  
Jong Oh Kim ◽  
Andrew Faramand ◽  
Kevin Fallon ◽  
John Flickinger ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Stereotactic Radiosurgery ◽  
Gamma Knife ◽  
Tumor Volume ◽  
Median Number ◽  
Whole Brain Radiation ◽  
Clinical Scenarios ◽  
The Mean ◽  
Gamma Knife Stereotactic Radiosurgery ◽  
The Brain

OBJECTIVEThe use of Gamma Knife stereotactic radiosurgery (GKSRS) for the treatment of extensive intracranial metastases has been expanding due to its superior dosimetry and efficacy. However, there remains a dearth of data regarding the dose parameters in actual clinical scenarios. The authors endeavored to calculate the radiation dose to the brain when treating ≥ 15 brain metastases with GKSRS.METHODSThis retrospective analysis reviewed dosage characteristics for patients requiring single-session GKSRS for the treatment of ≥ 15 brain metastases. Forty-two patients met the inclusion criteria between 2008 and 2017. The median number of tumors at the initial GKSRS procedure was 20 (range 15–39 tumors), accounting for 865 tumors in this study. The median aggregate tumor volume was 3.1 cm3 (range 0.13–13.26 cm3), and the median marginal dose was 16 Gy (range 14–19 Gy).RESULTSThe median of the mean brain dose was 2.58 Gy (range 0.95–3.67 Gy), and 79% of patients had a dose < 3 Gy. The 12-Gy dose volume was a median of 12.45 cm3, which was equivalent to 0.9% of the brain volume. The median percentages of brain receiving 5 Gy and 3 Gy were 6.7% and 20.4%, respectively. There was no correlation between the number of metastases and the mean dose to the brain (p = 0.8). A greater tumor volume was significantly associated with an increased mean brain dose (p < 0.001). The median of the mean dose to the bilateral hippocampi was 2.3 Gy. Sixteen patients had supplementary GKSRS, resulting in an additional mean dose of 1.4 Gy (range 0.2–3.8 Gy) to the brain.CONCLUSIONSGKSRS is a viable means of managing extensive brain metastases. This procedure provides a relatively low dose of radiation to the brain, especially when compared with traditional whole-brain radiation protocols.

Gamma Knife Radiosurgery for High-Grade Gliomas: Single-Center Experience of Six Years in China

2021 ◽  
Vol 99 (3) ◽  
pp. 181-186
Author(s):  
Ming Zhao ◽  
Xiangping Fu ◽  
Zhiwen Zhang ◽  
Liang Ma ◽  
Xiaopeng Wang ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Cox Regression ◽  
Survival Rates ◽  
Gamma Knife Radiosurgery ◽  
Progression Free Survival ◽  
High Grade Glioma ◽  
Karnofsky Performance Score ◽  
High Grade ◽  
Alternative Treatment Option ◽  
The Mean

<b><i>Objective:</i></b> The aim of this study was to evaluate the efficacy of Gamma Knife radiosurgery (GKRS) as a salvage therapy for high-grade glioma in our center. <b><i>Methods:</i></b> A total of 167 patients with malignant glioma were treated with GKRS in our Gamma Knife Center between January 2013 and December 2017; 140 patients (85 males and 55 females) were followed up and enrolled in our study. A single lesion was found in 110 cases, and multiple lesions were found in 30 cases; 108 cases received a single therapy, and in 32 cases, at least 2 GKRSs were performed. The median tumor volume was 13.5 cm<sup>3</sup>. The mean radiation dosage was 14.35 Gy (range, 6–18 Gy). MRI was performed regularly. The RANO criteria and Cox analysis were used to evaluate the therapeutic efficiency. <b><i>Results:</i></b> Follow-up MRI showed the local control rate was 61.4% at 3 months after GKRS, 25.0% at 6 months, and 7.1% at 12 months. The mean and median progression-free survival (PFS) periods were 8.6 (95% CI, 6.3–11.0) and 4 (95% CI, 3.5–4.5) (range, 1–60) months, respectively. The overall survival (OS) after GKRS was 3–62 months, with a mean of 16.7 (95% CI, 14.6–18.9) months, and the median survival was 13 (95% CI, 12.1–13.9) months. The 1-, 2-, and 5-year survival rates were 51.4, 10.0, and 2.9%, respectively. No severe complications occurred. Cox regression showed that glioma pathology was closely related to prognosis (<i>p</i> &#x3c; 0.05). The Karnofsky Performance Score had little influence on PFS (<i>p</i> &#x3e; 0.05) but influenced OS significantly (<i>p</i> &#x3c; 0.05). <b><i>Conclusion:</i></b> GKRS can be used to effectively treat malignant brain glioma and can therefore be used as an alternative treatment option.

Outcomes of stereotactic radiosurgery for pilocytic astrocytoma: an international multiinstitutional study

2021 ◽  
Vol 134 (1) ◽  
pp. 162-170 ◽  
Author(s):  
Erin S. Murphy ◽  
Shireen Parsai ◽  
Hideyuki Kano ◽  
Jason P. Sheehan ◽  
Roberto Martinez-Alvarez ◽  
...  
Keyword(s):  
Overall Survival ◽  
Stereotactic Radiosurgery ◽  
Pilocytic Astrocytoma ◽  
Univariate Analysis ◽  
Survival Rates ◽  
Gamma Knife Radiosurgery ◽  
Initial Therapy ◽  
Single Session ◽  
Current Standard

OBJECTIVEThe current standard initial therapy for pilocytic astrocytoma is maximal safe resection. Radiation therapy is considered for residual, recurrent, or unresectable pilocytic astrocytomas. However, the optimal radiation strategy has not yet been established. Here, the authors describe the outcomes of stereotactic radiosurgery (SRS) for pilocytic astrocytoma in a large multiinstitutional cohort.METHODSAn institutional review board–approved multiinstitutional database of patients treated with Gamma Knife radiosurgery (GKRS) between 1990 and 2016 was queried. Data were gathered from 9 participating International Radiosurgery Research Foundation (IRRF) centers. Patients with a histological diagnosis of pilocytic astrocytoma treated using a single session of GKRS and with at least 6 months of follow-up were included in the analysis.RESULTSA total of 141 patients were analyzed in the study. The median patient age was 14 years (range 2–84 years) at the time of GKRS. The median follow-up was 67.3 months. Thirty-nine percent of patients underwent SRS as the initial therapy, whereas 61% underwent SRS as salvage treatment. The median tumor volume was 3.45 cm3. The tumor location was the brainstem in 30% of cases, with a nonbrainstem location in the remainder. Five- and 10-year overall survival rates at the last follow-up were 95.7% and 92.5%, respectively. Five- and 10-year progression-free survival (PFS) rates were 74.0% and 69.7%, respectively. On univariate analysis, an age < 18 years, tumor volumes < 4.5 cm3, and no prior radiotherapy or chemotherapy were identified as positive prognostic factors for improved PFS. On multivariate analysis, only prior radiotherapy was significant for worse PFS.CONCLUSIONSThis represents the largest study of single-session GKRS for pilocytic astrocytoma to date. Favorable long-term PFS and overall survival were observed with GKRS. Further prospective studies should be performed to evaluate appropriate radiosurgery dosing, timing, and sequencing of treatment along with their impact on toxicity and the quality of life of patients with pilocytic astrocytoma.

Gamma Knife stereotactic radiosurgery in the treatment of brain metastases from breast cancer

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 10555-10555
Author(s):  
R. Gutt ◽  
S. Yovino ◽  
L. Chin ◽  
W. Regine ◽  
P. Amin ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Brain Metastases ◽  
Stereotactic Radiosurgery ◽  
Gamma Knife ◽  
Karnofsky Performance Status ◽  
Systemic Disease ◽  
Univariate Analysis ◽  
Complication Rates ◽  
Gamma Knife Stereotactic Radiosurgery

10555 Background: Outcomes of gamma knife stereotactic radiosurgery (GK-SRS) for patients with brain metastases specifically from breast cancer have not been well-defined. This study was undertaken to report the long-term experience with GK-SRS in this subset of patients. Methods: From 1995 to 2005, 75 patients with 162 brain lesions were treated with GK-SRS at the University of Maryland Medical Center. Complete follow-up data were available in 65 patients. Additional whole brain radiation therapy (WBRT) was administered to 53 (81.5%) patients. The median WBRT dose was 36.75 Gy (30.0–45.0 Gy). The median number of lesions treated with GK-SRS was 2 (1–8 lesions). The median follow-up, age, and KPS were 7.2 months (0.4–75.7 months), 53.5 years (23–81 years), and 90 (40–100), respectively. The factors included in the univariate and multivariate analyses for overall survival (OS) and progression free survival (PFS) were age, Karnofsky Performance Status (KPS), tumor histology, estrogen receptor status, Her-2-neu status, number of intracranial lesions, and presence of systemic disease. Results: Median PFS and OS from GK-SRS were 5.3 months (0.4–33.2 months) and 8.1 months (0.4–75.7 months), respectively. The 6, 12, and 24 month actuarial PFS were 47.8%, 24.9%, and 9.6% respectively. The 6, 12, and 24 month actuarial OS were 60.7%, 39.1%, and 18.1% respectively. The tumor local control after WBRT and GK-SRS was 87.7%. Radiation necrosis was a complication in 10.8% of patients. Forty-seven (72.3%) patients had neurological symptoms prior to gamma knife treatment. Seven (14.9%) and 9 (19.1%) of these patients experienced symptom resolution and significant symptomatic improvement, respectively. Multivariate and univariate analysis did not reveal any of the prognostic factors in question to be significantly associated with OS nor PFS. Conclusions: This relatively large cohort of patients experienced poor survival outcomes despite aggressive therapy with WBRT and GK-SRS. However, GK-SRS can provide significant symptomatic relief, with acceptable complication rates. More research is required to improve the survival of breast cancer patients with intracranial metastases. No significant financial relationships to disclose.

scholarly journals OS8.3 Gamma knife radiosurgery for large meningiomas: 10 years of experience

2019 ◽  
Vol 21 (Supplement_3) ◽  
pp. iii16-iii16
Author(s):  
K Abdel Karim ◽  
A El-Shehaby ◽  
W Reda ◽  
R Emad Eldin ◽  
A Nabeel ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Radiation Effects ◽  
Gamma Knife Radiosurgery ◽  
Long Term Results ◽  
Tumor Control ◽  
Safe Treatment ◽  
Intracranial Meningiomas ◽  
Prescription Dose ◽  
The Mean

Abstract BACKGROUND The use of gamma knife radiosurgery for the treatment of intracranial meningiomas has been established as an effective and safe treatment modality. Larger meningiomas are typically managed by surgery followed by radiosurgery. For situations where patients are not amenable to surgery fractionated stereotactic radiotherapy is the traditionally suggested treatment. Treatment of large meningiomas (usually defined as >10 cc) by stereotactic radiosurgery has been investigated in some recent reports, either by single-session, volume-staged or hypofractionation technique. However, there are no long-term results. The purpose of this study is to assess the long-term efficacy and safety of gamma knife radiosurgery for large (15 cc or more) intracranial meningiomas. MATERIAL AND METHODS In this study we included 80 patients with large meningiomas (³ 15 cc) who were followed up for more than 5 years. Non-benign meningiomas were excluded. Also, meningiomatosis and NF2 patients were not included. There were 18 males (22.5%) and 62 females (77.5%). The mean age was 46 years (20–83 years). Twenty-six patients (32.5%) had previous surgery. Tumor were supratentorial in 14 (17.5%) patients and skull base in 66 (82.5%) patients. The mean tumor volume was 22.3 cc (15–57.3 cc). The mean prescription dose was 11 Gy (9–12 Gy). RESULTS The mean follow up period was 8.4 years (5–17 years). The tumor shrank in 43 patients (54%), was stable in 30 patients (37%) and progressed in 7 patients (8%). The tumor control rate was 91%. Adverse radiation effects were observed in 11 patients (14%) but only 5 (6.5%) were symptomatic. These were temporary in all cases. CONCLUSION Gamma knife radiosurgery provides an effective and safe treatment option for large meningiomas. Low margin dose appears to be sufficient for tumor control. Surgery remains the first option in these cases.

scholarly journals Gamma Knife surgery for treating brain metastases arising from hepatocellular carcinomas

2014 ◽  
Vol 121 (Suppl_2) ◽  
pp. 102-109 ◽  
Author(s):  
Eun Suk Park ◽  
Do Hoon Kwon ◽  
Jun Bum Park ◽  
Do Hee Lee ◽  
Young Hyun Cho ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Gamma Knife ◽  
Univariate Analysis ◽  
Radiation Therapy Oncology Group ◽  
Local Tumor Control ◽  
Gamma Knife Surgery ◽  
Tumor Control ◽  
Significant Variable ◽  
Local Tumor ◽  
The Mean

ObjectBrain metastases from hepatocellular carcinoma (HCC) are rare, and the evidence of the effectiveness of Gamma Knife surgery (GKS) in this disease is lacking. The authors report their institutional experience with GKS in patients with brain metastases from HCCs.MethodsThe authors retrospectively reviewed the medical records of 73 consecutive patients who had a combined total of 141 brain metastases arising from HCCs and were treated with GKS. Sixty-four (87.7%) patients were male, and the mean age of the patients was 52.5 years (range 30–79 years). The mean tumor volume was 7.35 cm3 (range 0.19–33.7 cm3). The median margin dose prescribed was 23 Gy (range 15–32 Gy). Univariate and multivariate survival analyses were performed to identify possible prognostic factors of outcomes.ResultsThe estimated rate of local tumor control was 79.6% at 3 months after GKS. The median overall survival time after GKS was 16 weeks. The actuarial survival rates were 76.7%, 58.9%, and 26.0% at 4, 12, and 24 weeks after GKS, respectively. In the univariate analysis, an age of ≤ 65 years, Child-Pugh Class A (pertaining to liver function), high Karnofsky Performance Scale score (≥ 70), and low Radiation Therapy Oncology Group recursive partitioning analysis class (I or II) were positively associated with the survival times of patients. No statistically significant variable was identified in the multivariate analysis.ConclusionsAlthough survival was extremely poor in patients with brain metastases from HCCs, GKS showed acceptable local tumor control at 3 months after the treatment. The authors suggest that GKS represents a noninvasive approach that may provide a valuable option for treating patients with brain metastases from HCCs.

Clinical and Pathological Characteristics of Brain Metastasis Resected After Failed Radiosurgery

Neurosurgery ◽  
2010 ◽  
Vol 66 (1) ◽  
pp. 208-217 ◽  
Author(s):  
Jay Jagannathan ◽  
T. David Bourne ◽  
David Schlesinger ◽  
Chun-Po Yen ◽  
Mark E. Shaffrey ◽  
...  
Keyword(s):  
Brain Metastasis ◽  
Brain Metastases ◽  
Cell Carcinoma ◽  
Gamma Knife ◽  
Gamma Knife Radiosurgery ◽  
Proliferation Index ◽  
Time Interval ◽  
Cell Lung Carcinoma ◽  
Viable Tumor ◽  
The Mean

Abstract OBJECTIVE This study evaluates the tumor histopathology and clinical characteristics of patients who underwent resection of their brain metastasis after failed gamma knife radiosurgery. METHODS This study was a retrospective review from a prospective database. A total of 1200 brain metastases in 912 patients were treated by gamma knife radiosurgery during a 7-year period. Fifteen patients (1.6% of patients, 1.2% of all brain metastases) underwent resective surgery for either presumed tumor progression (6 patients) or worsening neurological symptoms associated with increased mass effect (9 patients). Radiographic imaging, radiosurgical and surgical treatment parameters, histopathological findings, and long-term outcomes were reviewed for all patients. RESULTS The mean age at the time of radiosurgery was 57 years (age range, 32–65 years). Initial pathological diagnoses included metastatic non–small cell lung carcinoma in 8 patients (53%), melanoma in 4 patients (27%), renal cell carcinoma in 2 patients (13%), and squamous cell carcinoma of the tongue in 1 patient (7%). The mean time interval between radiosurgery and surgical extirpation was 8.5 months (range, 3 weeks to 34 months). The mean treatment volume for the resected lesion at the time of radiosurgery was 4.4 cm3 (range, 0.6–8.4 cm3). The mean dose to the tumor margin was 21Gy (range, 18–24 Gy). In addition to the 15 tumors that were eventually resected, a total of 32 other metastases were treated synchronously, with a 78% control rate. The mean volume immediately before surgery for the 15 resected lesions was 7.5 cm3 (range, 3.8–10.2 cm3). Histological findings after radiosurgery varied from case to case and included viable tumor, necrotic tumor, vascular hyalinization, hemosiderin-laden macrophages, reactive gliosis in surrounding brain tissue, and an elevated MIB-1 proliferation index in cases with viable tumor. The mean survival for patients in whom viable tumor was identified (9.4 months) was significantly lower than that of patients in whom only necrosis was seen (15.1 months; Fisher's exact test, P &lt; 0.05). CONCLUSION Radiation necrosis and tumor radioresistance are the most common causes precipitating a need for surgical resection after radiosurgery in patients with brain metastasis.

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