Stereotactic radiosurgery at a low marginal dose for the treatment of pediatric arteriovenous malformations: obliteration, complications, and functional outcomes

OBJECT.: Stereotactic radiosurgery (SRS) is an established treatment modality for brain arteriovenous malformations (AVMs) in children, but the optimal treatment parameters and associated treatment-related complications are not fully understood. The authors present their single-institution experience of using SRS, at a relatively low marginal dose, to treat AVMs in children for nearly 20 years; they report angiographic outcomes, posttreatment hemorrhage rates, adverse treatment-related events, and functional outcomes.

METHODS

The authors conducted a retrospective review of 2 cohorts of children (18 years of age or younger) with AVMs treated from 1991 to 1998 and from 2000 to 2010.

RESULTS

A total of 80 patients with follow-up data after SRS were identified. Mean age at SRS was 12.7 years, and 56% of patients had hemorrhage at the time of presentation. Median target volume was 3.1 cm(3) (range 0.09-62.3 cm(3)), and median prescription marginal dose used was 17.5 Gy (range 12-20 Gy). Angiograms acquired 3 years after treatment were available for 47% of patients; AVM obliteration was achieved in 52% of patients who received a dose of 18-20 Gy and in 16% who received less than 18 Gy. At 5 years after SRS, the cumulative incidence of hemorrhage was 25% (95% CI 16%-37%). No permanent neurological deficits occurred in patients who did not experience posttreatment hemorrhage. Overall, good functional outcomes (modified Rankin Scale Scores 0-2) were observed for 78% of patients; for 66% of patients, functional status improved or remained the same as before treatment.

CONCLUSIONS

A low marginal dose minimizes SRS-related neurological deficits but leads to low rates of obliteration and high rates of hemorrhage. To maximize AVM obliteration and minimize posttreatment hemorrhage, the authors recommend a prescription marginal dose of 18 Gy or more. In addition, SRS-related symptoms such as headache and seizures should be considered when discussing risks and benefits of SRS for treating AVMs in children.

Deep arteriovenous malformations in the basal ganglia, thalamus, and insula: multimodality management, patient selection, and results

OBJECTIVE

This study sought to describe a single institution's experience treating arteriovenous malformations (AVMs) of the basal ganglia, thalamus, and insula in a multimodal fashion.

METHODS

We conducted a retrospective review of all deep AVMs treated at our institution between 1997 and 2011 with attention to patient selection, treatment strategies, and radiographic and functional outcomes.

RESULTS

A total of 97 patients underwent initial treatment at our institution. 64% presented with hemorrhage with 29% located in the basal ganglia, 41% in the thalamus, and 30% in the insula. 80% were Spetzler-Martin grade III-IV. Initial treatment was microsurgical resection in 42%, stereotactic radiosurgery (SRS) in 45%, and observation in 12%. Radiographic cure was achieved in 54% after initial surgical or SRS treatment (71% and 23%, respectively) and in 63% after subsequent treatments, with good functional outcomes in 78% (median follow-up 2.2 years). Multivariate logistic regression analysis revealed treatment group and age as factors associated with radiographic cure, whereas Spetzler-Martin score and time to follow-up were significantly associated with improved/unchanged functional status at time of last follow-up. Posttreatment hemorrhage occurred in 11% (7% of surgical and 18% of SRS patients).

CONCLUSIONS

Modern treatment of deep AVMs includes a multidisciplinary approach utilizing microsurgery, SRS, embolization, and observation. Supplementary grading adds meaningfully to traditional Spetzler-Martin grading to guide patient selection. Surgical resection is more likely to result in obliteration compared with SRS, and is associated with satisfactory results in carefully selected patients.

Angiographic features help predict outcome after stereotactic radiosurgery for the treatment of pediatric arteriovenous malformations

PURPOSE

Arteriovenous malformations (AVMs) are a frequent cause of hemorrhagic stroke in children. Stereotactic radiosurgery (SRS) is an established treatment for these lesions, particularly those that are surgically inaccessible. Because only complete AVM obliteration is believed to protect against the future risk of hemorrhage, identifying lesion characteristics that predict response to therapy is an important objective. The goal of this study is to evaluate the influence of angiographic features of AVMs on the rate of obliteration following treatment with SRS.

METHODS

This is a retrospective cohort study of pediatric patients (age ≤18 years) treated with Gamma Knife SRS for cerebral AVMs between 2000 and 2012. Detailed angiographic data at the time of initial angiographic evaluation were prospectively recorded by experienced neurointerventional radiologists. The primary outcome was the rate of obliteration on a 3-year follow-up angiogram.

RESULTS

We identified 42 pediatric patients treated with SRS for cerebral AVMs. Twenty-seven patients completed 3-year angiographic follow-ups. Complete obliteration was seen in 30%, partial response in 67%, and no response in 4%. Higher SRS dose was associated with complete obliteration. Larger AVM diameter, presence of multiple draining veins, and presence of multiple draining veins reaching a sinus were associated with partial response. In this small cohort, diffuse AVM borders, presence of aneurysm, and pre-SRS embolization were not associated with obliteration.

CONCLUSIONS

Our study identifies AVMs in the pediatric population with a nidus diameter of <2.5 cm and a solitary draining vein as the most likely to undergo complete obliteration after SRS treatment.

Whole-procedural radiological accuracy for delivering multi-session gamma knife radiosurgery with a relocatable frame system

A newly developed Gamma Knife relocatable eXtend frame system has enabled the delivery of multi-session Gamma Knife radiosurgery without the use of skull pin fixation frame system. In this study, we investigate and report for the first time the whole procedural radiological accuracy for administering such treatments. To quantify the radiological alignment, the commonly used Winston-Lutz test was modified and used to determine the device accuracy of the eXtend frame system. Patient setup uncertainties relative to the device were further measured for a series of treatment sessions (n = 58), and then incorporated with the Winston-Lutz test results from individual patient-specific eXtend frame systems. The whole-procedure mean 3D radiological setup uncertainty was determined to be 0.69 ± 0.73 mm (1σ) from all the cases analyzed, and the mean 90% confidence level margins were found to be 0.55, 0.78 and 0.72 mm along the x-, y-, and z-axis, respectively. Our results therefore demonstrated that sub-millimetric radiological accuracy is clinically achievable for multi-session Gamma Knife radiosurgery treatments and a 1 mm margin along the major axes is sufficient for planning multi-session Gamma Knife radiosurgery treatments.

Gamma Knife radiosurgery for the management of nonfunctioning pituitary adenomas: a multicenter study

Object

Pituitary adenomas are fairly common intracranial neoplasms, and nonfunctioning ones constitute a large subgroup of these adenomas. Complete resection is often difficult and may pose undue risk to neurological and endocrine function. Stereotactic radiosurgery has come to play an important role in the management of patients with nonfunctioning pituitary adenomas. This study examines the outcomes after radiosurgery in a large, multicenter patient population.

Methods

Under the auspices of the North American Gamma Knife Consortium, 9 Gamma Knife surgery (GKS) centers retrospectively combined their outcome data obtained in 512 patients with nonfunctional pituitary adenomas. Prior resection was performed in 479 patients (93.6%) and prior fractionated external-beam radiotherapy was performed in 34 patients (6.6%). The median age at the time of radiosurgery was 53 years. Fifty-eight percent of patients had some degree of hypopituitarism prior to radiosurgery. Patients received a median dose of 16 Gy to the tumor margin. The median follow-up was 36 months (range 1–223 months).

Results

Overall tumor control was achieved in 93.4% of patients at last follow-up; actuarial tumor control was 98%, 95%, 91%, and 85% at 3, 5, 8, and 10 years postradiosurgery, respectively. Smaller adenoma volume (OR 1.08 [95% CI 1.02–1.13], p = 0.006) and absence of suprasellar extension (OR 2.10 [95% CI 0.96–4.61], p = 0.064) were associated with progression-free tumor survival. New or worsened hypopituitarism after radiosurgery was noted in 21% of patients, with thyroid and cortisol deficiencies reported as the most common postradiosurgery endocrinopathies. History of prior radiation therapy and greater tumor margin doses were predictive of new or worsening endocrinopathy after GKS. New or progressive cranial nerve deficits were noted in 9% of patients; 6.6% had worsening or new onset optic nerve dysfunction. In multivariate analysis, decreasing age, increasing volume, history of prior radiation therapy, and history of prior pituitary axis deficiency were predictive of new or worsening cranial nerve dysfunction. No patient died as a result of tumor progression. Favorable outcomes of tumor control and neurological preservation were reflected in a 4-point radiosurgical pituitary score.

Conclusions

Gamma Knife surgery is an effective and well-tolerated management strategy for the vast majority of patients with recurrent or residual nonfunctional pituitary adenomas. Delayed hypopituitarism is the most common complication after radiosurgery. Neurological and cranial nerve function were preserved in more than 90% of patients after radiosurgery. The radiosurgical pituitary score may predict outcomes for future patients who undergo GKS for a nonfunctioning adenoma.

Reliability of contour-based volume calculation for radiosurgery

OBJECT

Determining accurate target volume is critical for both prescribing and evaluating stereotactic radiosurgery (SRS) treatments. The aim of this study was to determine the reliability of contour-based volume calculations made by current major SRS platforms.

METHODS

Spheres ranging in diameter from 6.4 to 38.2 mm were scanned and then delineated on imaging studies. Contour data sets were subsequently exported to 6 SRS treatment-planning platforms for volume calculations and comparisons. This procedure was repeated for the case of a patient with 12 metastatic lesions distributed throughout the brain. Both the phantom and patient datasets were exported to a stand-alone workstation for an independent volume-calculation analysis using a series of 10 algorithms that included approaches such as slice stacking, surface meshing, point-cloud filling, and so forth.

RESULTS

Contour data-rendered volumes exhibited large variations across the current SRS platforms investigated for both the phantom (-3.6% to 22%) and patient case (1.0%-10.2%). The majority of the clinical SRS systems and algorithms overestimated the volumes of the spheres, compared with their known physical volumes. An independent algorithm analysis found a similar trend in variability, and large variations were typically associated with small objects whose volumes were < 0.4 cm(3) and with those objects located near the end-slice of the scan limits.

CONCLUSIONS

Significant variations in volume calculation were observed based on data obtained from the SRS systems that were investigated. This observation highlights the need for strict quality assurance and benchmarking efforts when commissioning SRS systems for clinical use and, moreover, when conducting multiinstitutional cross-SRS platform clinical studies.

High-precision volume-staged Gamma Knife surgery and equivalent hypofractionation dose schedules for treating large arteriovenous malformations

OBJECT

The goal of this study was to develop a technique for performing submillimeter high-precision volume-staged Gamma Knife surgery and investigate its potential benefits in comparison with hypofractionated stereotactic radiotherapy (SRT) for treating large arteriovenous malformations (AVMs).

METHODS

The authors analyzed 7 pediatric AVM cases treated with volume-staged stereotactic radiosurgery (SRS) using the Gamma Knife Perfexion at the University of California, San Francisco. The target and normal tissue contours from each case were exported for hypofractionated treatment planning based on the Gamma Knife Extend system or the CyberKnife SRT. Both the Gamma Knife Extend and CyberKnife treatment plans were matched to yield the same level of target coverage (95%-98%) and conformity indices (1.24-1.46). Finally, hypofractionated treatment plans were compared with volume-staged treatment plans for sparing normal brain by using biologically equivalent 12-Gy normal brain volumes.

RESULTS

Hypofractionated Gamma Knife Extend and CyberKnife treatment plans exhibited practically identical sparing of normal brain for the studied cases. However, when matching such values with volume-staged treatments for the biological effective dose, only conservative dose fractionation schemes, such as 27.3 Gy in 5 fractions and 25 Gy in 4 fractions, were found to be comparable to the volume-staged treatments. On average, this represents a mean 18.7% ± 7.3% reduction in the single-fraction biologically equivalent dose for hypofractionated treatments versus the reference volume-staged treatments (p < 0.001).

CONCLUSIONS

Volume staging remains advantageous over hypofractionation in delivering a higher dose to the target and for better sparing of normal brain tissue in the treatment of large AVMs. More clinical data are needed, however, to justify the clinical superiority of this increased dose when compared with a hypofractionated treatment regimen.

A technique for achieving submillimeter accuracy of volume-staged stereotactic radiosurgery

A technique for delivering high-precision volume-staged stereotactic radiosurgery has been developed with Leksell Gamma Knife Perfexion for treating large arteriorvenous malformations (AVMs). The technique employs a hybrid method of combining landmark registration and voxel-based 3D image registration to enable multiple staged partial-volume treatments that accommodate repeated stereotactic frame placements. The technique was clinically implemented at our institution and the results were analyzed for a series (n=14) of large AVM cases treated since 2007. Overall, an averaged 0.34±0.09 mm in matching procedural accuracy versus standard single-fraction radiosurgery was found for these treatments. Such a result is a factor of 3-4 times lower than those previously reported, and it approaches the physical accuracy of the latest Leksell Gamma Knife Perfexion system. In conclusion, volume-staged radiosurgery has been demonstrated to be deliverable with the same level of accuracy as standard single-fraction radiosurgery.

Summary report on the graded prognostic assessment: an accurate and facile diagnosis-specific tool to estimate survival for patients with brain metastases

PURPOSE

Our group has previously published the Graded Prognostic Assessment (GPA), a prognostic index for patients with brain metastases. Updates have been published with refinements to create diagnosis-specific Graded Prognostic Assessment indices. The purpose of this report is to present the updated diagnosis-specific GPA indices in a single, unified, user-friendly report to allow ease of access and use by treating physicians.

METHODS

A multi-institutional retrospective (1985 to 2007) database of 3,940 patients with newly diagnosed brain metastases underwent univariate and multivariate analyses of prognostic factors associated with outcomes by primary site and treatment. Significant prognostic factors were used to define the diagnosis-specific GPA prognostic indices. A GPA of 4.0 correlates with the best prognosis, whereas a GPA of 0.0 corresponds with the worst prognosis.

RESULTS

Significant prognostic factors varied by diagnosis. For lung cancer, prognostic factors were Karnofsky performance score, age, presence of extracranial metastases, and number of brain metastases, confirming the original Lung-GPA. For melanoma and renal cell cancer, prognostic factors were Karnofsky performance score and the number of brain metastases. For breast cancer, prognostic factors were tumor subtype, Karnofsky performance score, and age. For GI cancer, the only prognostic factor was the Karnofsky performance score. The median survival times by GPA score and diagnosis were determined.

CONCLUSION

Prognostic factors for patients with brain metastases vary by diagnosis, and for each diagnosis, a robust separation into different GPA scores was discerned, implying considerable heterogeneity in outcome, even within a single tumor type. In summary, these indices and related worksheet provide an accurate and facile diagnosis-specific tool to estimate survival, potentially select appropriate treatment, and stratify clinical trials for patients with brain metastases.

Stereotactic Radiosurgery for Chordoma

BACKGROUND:

Although considered slow-growing, low-grade malignancies, chordomas are locally aggressive and destructive tumors with high recurrence rates.

OBJECTIVE:

To assess patient survival, tumor control, complications, and selected variables that predict outcome in patients who underwent Gamma Knife stereotactic radiosurgery (SRS) as primary, adjuvant, or salvage management for chordomas of the skull base.

METHODS:

Six participating centers of the North American Gamma Knife Consortium identified 71 patients who underwent SRS for chordoma. The median patient age was 45 years (range, 7-80 years). The median SRS target volume was 7.1 cm3 (range, 0.9-109 cm3), and median margin dose was 15.0 Gy (range, 9-25 Gy).

RESULTS:

At a median follow-up of 5 years (range, 0.6-14 years) after SRS, 23 patients died of tumor progression. The 5-year actuarial overall survival after SRS was 80% for the entire group, 93% for the no prior fractionated radiation therapy (RT) group (n = 50), and 43% for the prior RT group (n = 21). Younger age, longer interval between initial diagnosis and SRS, no prior RT, &lt; 2 cranial nerve deficits, and smaller total tumor volume were significantly associated with longer patient survival. The 5-year treated tumor control rate after SRS was 66% for the entire group, 69% for the no prior RT group, and 62% for the prior RT group. Older age, recurrent group, prior RT, and larger tumor volume were significantly associated with worse tumor control.

CONCLUSION:

Stereotactic radiosurgery is a potent treatment option for small sized chordomas, especially in younger patients and as part of a multipronged attack that includes surgical resection when possible.

A dosimetric comparison between Gamma Knife and CyberKnife treatment plans for trigeminal neuralgia

OBJECT

The Leksell Gamma Knife and the Accuray CyberKnife systems have been used in the radio surgical treatment of trigeminal neuralgia. The 2 techniques use different delivery methods and different treatment parameters. In the past, CyberKnife treatments have been associated with an increased incidence of treatment-related complications, such as facial numbness. The goal of this study was to develop a method for planning a CyberKnife treatment for trigeminal neuralgia that would reproduce the dosimetric characteristics of a Gamma Knife plan. A comparison between Gamma Knife and CyberKnife treatment plans obtained with this method is presented.

METHODS

Five patients treated using the Gamma Knife Perfexion Unit were selected for this study. All patients underwent CT cisternography to accurately identify the position of the trigeminal nerve. The Gamma Knife plans used either one 4-mm-diameter collimator or two coincident 4-mm collimators (one open and one with sector blocking) placed at identical isocenter coordinates. A maximum local dose of 80 Gy was prescribed. Critical structures and representative isodose lines were outlined in GammaPlan and exported to the CyberKnife treatment planning platform. CyberKnife treatments were developed using the 5-mm-diameter cone and the trigeminal node set, which provides an effective collimation diameter of 4 mm at the isocenter. The 60-Gy isodose volume imported from GammaPlan was used as the target in the CyberKnife plans. The CyberKnife treatments were optimized to achieve target dose and critical structure sparing similar to the Gamma Knife plans. Isocentric and nonisocentric delivery techniques were investigated. Treatment plans were compared in terms of dosimetric characteristics, delivery, and planning efficiency.

RESULTS

CyberKnife treatments using the 5-mm cone and the trigeminal node set can closely reproduce the dose distribution of Gamma Knife plans. CyberKnife isocentric and nonisocentric plans provide comparable results. The average length of the trigeminal nerve receiving a dose of 60 Gy was 4.5, 4.5, and 4.4 mm for Gamma Knife, nonisocentric CyberKnife, and isocentric CyberKnife, respectively. However, minimizing the dose to the critical structures was more difficult with the CyberKnife and required the use of tuning structures. In addition, the dose fall off away from the target was steeper in Gamma Knife plans, probably due to the larger number of beams (192 beams for perfexion vs ~ 100 beams for cyberknife). While the treatment time with the cyberknife is generally shorter, the planning time is significantly longer.

CONCLUSIONS

CyberKnife radiosurgical parameters can be optimized to mimic the dose distribution of Gamma Knife plans. However, Gamma Knife plans result in superior sparing of critical structures (brainstem, temporal lobe,and cranial nerves VII and VIII) and in steeper dose fall off away from the target. The clinical significance of these effects is unknown. (DOI: 10.3171/2010.8.GKS101002)

A dosimetric comparison between Gamma Knife and CyberKnife treatment plans for trigeminal neuralgia

Object

The Leksell Gamma Knife and the Accuray CyberKnife systems have been used in the radiosurgical treatment of trigeminal neuralgia. The 2 techniques use different delivery methods and different treatment parameters. In the past, CyberKnife treatments have been associated with an increased incidence of treatment-related complications, such as facial numbness. The goal of this study was to develop a method for planning a CyberKnife treatment for trigeminal neuralgia that would reproduce the dosimetric characteristics of a Gamma Knife plan. A comparison between Gamma Knife and CyberKnife treatment plans obtained with this method is presented.

Methods

Five patients treated using the Gamma Knife Perfexion Unit were selected for this study. All patients underwent CT cisternography to accurately identify the position of the trigeminal nerve. The Gamma Knife plans used either one 4-mm-diameter collimator or two coincident 4-mm collimators (one open and one with sector blocking) placed at identical isocenter coordinates. A maximum local dose of 80 Gy was prescribed. Critical structures and representative isodose lines were outlined in GammaPlan and exported to the CyberKnife treatment planning platform. CyberKnife treatments were developed using the 5-mm-diameter cone and the trigeminal node set, which provides an effective collimation diameter of 4 mm at the isocenter. The 60-Gy isodose volume imported from GammaPlan was used as the target in the CyberKnife plans. The CyberKnife treatments were optimized to achieve target dose and critical structure sparing similar to the Gamma Knife plans. Isocentric and nonisocentric delivery techniques were investigated. Treatment plans were compared in terms of dosimetric characteristics, delivery, and planning efficiency.

Results

CyberKnife treatments using the 5-mm cone and the trigeminal node set can closely reproduce the dose distribution of Gamma Knife plans. CyberKnife isocentric and nonisocentric plans provide comparable results. The average length of the trigeminal nerve receiving a dose of 60 Gy was 4.5, 4.5, and 4.4 mm for Gamma Knife, nonisocentric CyberKnife, and isocentric CyberKnife, respectively. However, minimizing the dose to the critical structures was more difficult with the CyberKnife and required the use of tuning structures. In addition, the dose falloff away from the target was steeper in Gamma Knife plans, probably due to the larger number of beams (192 beams for Perfexion vs ~ 100 beams for CyberKnife). While the treatment time with the CyberKnife is generally shorter, the planning time is significantly longer.

Conclusions

CyberKnife radiosurgical parameters can be optimized to mimic the dose distribution of Gamma Knife plans. However, Gamma Knife plans result in superior sparing of critical structures (brainstem, temporal lobe, and cranial nerves VII and VIII) and in steeper dose falloff away from the target. The clinical significance of these effects is unknown.

Diagnosis-specific prognostic factors, indexes, and treatment outcomes for patients with newly diagnosed brain metastases: a multi-institutional analysis of 4,259 patients

PURPOSE

Controversy endures regarding the optimal treatment of patients with brain metastases (BMs). Debate persists, despite many randomized trials, perhaps because BM patients are a heterogeneous population. The purpose of the present study was to identify significant diagnosis-specific prognostic factors and indexes (Diagnosis-Specific Graded Prognostic Assessment [DS-GPA]).

METHODS AND MATERIALS

A retrospective database of 5,067 patients treated for BMs between 1985 and 2007 was generated from 11 institutions. After exclusion of the patients with recurrent BMs or incomplete data, 4,259 patients with newly diagnosed BMs remained eligible for analysis. Univariate and multivariate analyses of the prognostic factors and outcomes by primary site and treatment were performed. The significant prognostic factors were determined and used to define the DS-GPA prognostic indexes. The DS-GPA scores were calculated and correlated with the outcomes, stratified by diagnosis and treatment.

RESULTS

The significant prognostic factors varied by diagnosis. For non-small-cell lung cancer and small-cell lung cancer, the significant prognostic factors were Karnofsky performance status, age, presence of extracranial metastases, and number of BMs, confirming the original GPA for these diagnoses. For melanoma and renal cell cancer, the significant prognostic factors were Karnofsky performance status and the number of BMs. For breast and gastrointestinal cancer, the only significant prognostic factor was the Karnofsky performance status. Two new DS-GPA indexes were thus designed for breast/gastrointestinal cancer and melanoma/renal cell carcinoma. The median survival by GPA score, diagnosis, and treatment were determined.

CONCLUSION

The prognostic factors for BM patients varied by diagnosis. The original GPA was confirmed for non-small-cell lung cancer and small-cell lung cancer. New DS-GPA indexes were determined for other histologic types and correlated with the outcome, and statistical separation between the groups was confirmed. These data should be considered in the design of future randomized trials and in clinical decision-making.

Prognostic factors and grading systems for overall survival in patients treated with radiosurgery for brain metastases: variation by primary site

OBJECT

The authors conducted a study to determine whether prognostic factors and the applicability of prognostic systems vary by primary tumor site in patients treated with radiosurgery for brain metastases.

METHODS

The authors evaluated data obtained in patients who underwent radiosurgery with or without whole-brain radiotherapy (WBRT) from 1991 to 2005 for newly diagnosed brain metastases. Four groups were analyzed: 1) all primary sites combined, 2) breast, 3) lung, and 4) melanoma primary sites. Kaplan-Meier, log-rank, Cox proportional hazard uni- and multivariate analysis, and recursive partitioning analysis (RPA) were used to assess prognostic factors and 4 prognostic systems: Radiation Therapy Oncology Group (RTOG) RPA, Graded Prognostic Assessment (GPA), basic score for brain metastases (BSBM), and the newly proposed Golden grading system (GGS). The GGS divides patients into 4 prognostic groups by age >or= 65 years, Karnofsky Performance Scale (KPS) score < 70, and known presence of extracranial metastases.

RESULTS

Data acquired in 479 newly diagnosed patients with 1664 lesions were analyzed. The median survival time from diagnosis of brain metastases was 12.1 months; the median follow-up was 25.4 months in 73 patients who were censored. Survival and prognostic factors were equivalent for 369 patients treated with radiosurgery compared with 110 patients treated with radiosurgery and WBRT, so these subsets were combined. Multivariate analysis of all primary sites combined demonstrated age < 65 years, KPS score >or= 70, no known extracranial metastases, and <or= 3 brain metastases were associated with longer survival, and primary tumor control was not. In subgroup multivariate analysis of patients with breast, lung, or melanoma primaries, favorable factors included only primary tumor control in 87 patients with breast primary; age < 65 years, no known extracranial metastases, and <or= 3 brain metastases in 169 patients with lung primary; and KPS >or= 70 years, primary tumor control, and <or= 3 brain metastases in 137 patients with melanoma primary. The median survival for <or= 3 versus > 3 metastases was 15.6 and 16.9 months, respectively, for breast, 16.5 and 11.3 months for lung, and 9.0 and 5.7 months for melanoma. Analysis of the 4 prognostic systems (RTOG RPA, BSBM, GPA, and GGS) showed that each prognostic system's clinical applicability varied depending on primary tumor site. The RPA confirmed that GGS and primary tumor site are significant variables for prognosis.

CONCLUSIONS

Favorable prognostic factors for patients with newly diagnosed brain metastases treated with radiosurgery vary by primary site. The 4 prognostic grading systems analyzed were applicable to different primary sites depending on which prognostic factors each individual system incorporated. Therefore, the authors recommend further development and use of primary-specific prognostic systems.

Phase II study of erlotinib plus temozolomide during and after radiation therapy in patients with newly diagnosed glioblastoma multiforme or gliosarcoma

PURPOSE

This open-label, prospective, single-arm, phase II study combined erlotinib with radiation therapy (XRT) and temozolomide to treat glioblastoma multiforme (GBM) and gliosarcoma. The objectives were to determine efficacy of this treatment as measured by survival and to explore the relationship between molecular markers and treatment response.

PATIENTS AND METHODS

Sixty-five eligible adults with newly diagnosed GBM or gliosarcoma were enrolled. We intended to treat patients not currently treated with enzyme-inducing antiepileptic drugs (EIAEDs) with 100 mg/d of erlotinib during XRT and 150 mg/d after XRT. Patients receiving EIAEDs were to receive 200 mg/d of erlotinib during XRT and 300 mg/d after XRT. After XRT, the erlotinib dose was escalated until patients developed tolerable grade 2 rash or until the maximum allowed dose was reached. All patients received temozolomide during and after XRT. Molecular markers of epidermal growth factor receptor (EGFR), EGFRvIII, phosphatase and tensin homolog (PTEN), and methylation status of the promotor region of the MGMT gene were analyzed from tumor tissue. Survival was compared with outcomes from two historical phase II trials.

RESULTS

Median survival was 19.3 months in the current study and 14.1 months in the combined historical control studies, with a hazard ratio for survival (treated/control) of 0.64 (95% CI, 0.45 to 0.91). Treatment was well tolerated. There was a strong positive correlation between MGMT promotor methylation and survival, as well as an association between MGMT promotor-methylated tumors and PTEN positivity shown by immunohistochemistry with improved survival.

CONCLUSION

Patients treated with the combination of erlotinib and temozolomide during and following radiotherapy had better survival than historical controls. Additional studies are warranted.

Distinguishing recurrent intra-axial metastatic tumor from radiation necrosis following gamma knife radiosurgery using dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging

BACKGROUND AND PURPOSE

MR image-guided gamma knife radiosurgery is often used to treat intra-axial metastatic neoplasms. Following treatment, it is often difficult to determine whether a progressively enhancing lesion is due to metastatic tumor recurrence or radiation necrosis. The purpose of our study was to determine whether relative cerebral blood volume (rCBV), relative peak height (rPH), and percentage of signal-intensity recovery (PSR) derived from dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging can distinguish recurrent metastatic tumor from radiation necrosis.

MATERIALS AND METHODS

Twenty-seven patients with systemic cancer underwent gamma knife radiosurgery for metastatic lesions of the brain and subsequently developed enlarging regions of enhancement within the radiation field. Subsequent surgical resection or clinicoradiologic follow-up established a diagnosis of recurrent metastatic tumor or radiation necrosis. Perfusion MR imaging datasets were retrospectively reprocessed, and regions of interest were drawn around the entire contrast-enhancing region. The resulting T2* signal-intensity time curves produced rCBV, rPH, and PSR values for each examination. A Welch t test was used to compare imaging values between groups.

RESULTS

The mean, minimum, and maximum PSR values were significantly lower (P < .01) in cases of recurrent metastatic tumor. The mean and maximum rCBV and rPH values were significantly higher (P < .02) in the recurrent metastatic tumor group.

CONCLUSIONS

The findings of our study suggest that perfusion MR imaging may be used to differentiate recurrent intra-axial metastatic tumor from gamma knife-induced radiation necrosis.

Surgical resection and permanent iodine-125 brachytherapy for brain metastases

PURPOSE

To evaluate the efficacy and toxicity of surgical resection and permanent iodine-125 brachytherapy without adjuvant whole brain radiation therapy (WBRT) for brain metastases.

METHODS AND MATERIALS

Forty patients were treated with permanent iodine-125 brachytherapy at the time of resection of brain metastases from 1997 to 2003. Actuarial freedom from progression (FFP) and survival were measured from the date of surgery and estimated using the Kaplan-Meier method, with censoring at last imaging for FFP endpoints.

RESULTS

The median survival was 11.3 months overall, 12.0 months in 19 patients with newly diagnosed brain metastases and 7.3 months in 21 patients with recurrent brain metastases. Twenty-two patients (55%) remained free of progression of brain metastases, three failed at the resection cavity (including one with leptomeningeal dissemination), two failed with leptomeningeal spread only, and 13 failed elsewhere in the brain including two who also had leptomeningeal disease. The 1-year resection cavity FFP probabilities were 92%, 86% and 88%; and brain FFP probabilities were 29%, 43% and 37% for the newly diagnosed, recurrent and all patients, respectively. Symptomatic necrosis developed 7.4-40.0 months (median, 19.5 months) after brachytherapy in 9 patients (23%), confirmed by resection in 6 patients.

CONCLUSIONS

Excellent local control was achieved using permanent iodine-125 brachytherapy for brain metastasis resection cavities, although there is a high risk of radiation necrosis over time. These data support consideration of permanent brachytherapy without adjuvant WBRT as a treatment option in patients with symptomatic or large newly diagnosed or recurrent brain metastases.

Gamma knife radiosurgery for brainstem metastases: the UCSF experience

PURPOSE

To assess clinical and imaging outcomes in patients treated with Gamma Knife stereotactic radiosurgery (SRS) for brainstem metastases.

MATERIALS AND METHODS

We reviewed all patients with brain metastases treated with SRS at the University of California, San Francisco from 1991-2005 to identify patients who had SRS to a brainstem metastasis. Survival time and freedom from progression (FFP) were calculated from date of SRS using the Kaplan-Meier method. Prognostic factors were evaluated using the log-rank test and Cox proportional hazards model.

RESULTS

From 1991 through 2005, 42 consecutive patients with brainstem metastases had SRS to 44 lesions (seven midbrain, 31 pontine, and six medullary) in 42 sessions. Primary diagnoses included 14 cases of lung cancer (one small-cell), 10 melanoma, 12 breast cancer, five renal cell, and one unknown. The median age was 55 years (range, 25-79). The median survival time was 9 months after SRS. Longer survival time was associated with single metastasis, non-melanoma histology, and extracranial disease control. The median target volume was 0.26 ml (0.015-2.8 ml) and the median prescribed dose was 16.0 Gy (10.0-19.8 Gy). Brainstem lesion FFP was 90% at 6 months and 77% at 1 year. Four patients had brainstem complications following treatment. Poor brainstem outcome was associated with melanoma and renal cell histology as well as brainstem lesion volume > or =1 ml.

CONCLUSIONS

In this series, SRS using a median dose of 16 Gy provided excellent local control with relatively low morbidity in patients with brainstem metastases less than 1 ml or non-melanoma, non-renal cell histology.

Phase I trial of gross total resection, permanent iodine-125 brachytherapy, and hyperfractionated radiotherapy for newly diagnosed glioblastoma multiforme

PURPOSE

To evaluate the feasibility of gross total resection and permanent I-125 brachytherapy followed by hyperfractionated radiotherapy for patients with newly diagnosed glioblastoma.

METHODS AND MATERIALS

From April 1999 to May 2002, 21 patients with glioblastoma multiforme were enrolled on a Phase I protocol investigating planned gross total resection and immediate placement of permanent I-125 seeds, followed by postoperative hyperfractionated radiotherapy to a dose of 60 Gy at 100 cGy b.i.d., 5 days per week. Median age and Karnofsky performance status were 50 years (range, 32-65 years) and 90 (range, 70-100), respectively. Toxicity was assessed according to Radiation Therapy Oncology Group criteria.

RESULTS

Eighteen patients completed treatment according to protocol. The median preoperative tumor volume on magnetic resonance imaging was 18.6 cm(3) (range, 4.4-41.2 cm(3)). The median brachytherapy dose measured 5 mm radially outward from the resection cavity was 400 Gy (range, 200-600 Gy). Ten patients underwent 12 reoperations, with 11 of 12 reoperations demonstrating necrosis without evidence of tumor. Because of high toxicity, the study was terminated early. Median progression-free survival and overall survival were 57 and 114 weeks, respectively, but not significantly improved compared with historical patients treated at University of California, San Francisco, with gross total resection and radiotherapy without brachytherapy.

CONCLUSIONS

Treatment with gross total resection and permanent I-125 brachytherapy followed by hyperfractionated radiotherapy as performed in this study results in high toxicity and reoperation rates, without demonstrated improvement in survival.