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  • Author or Editor: Ian R. Crocker x
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Jaymin Jhaveri, Mudit Chowdhary, Xinyan Zhang, Robert H. Press, Jeffrey M. Switchenko, Matthew J. Ferris, Tiffany M. Morgan, Justin Roper, Anees Dhabaan, Eric Elder, Bree R. Eaton, Jeffrey J. Olson, Walter J. Curran Jr., Hui-Kuo G. Shu, Ian R. Crocker and Kirtesh R. Patel

OBJECTIVE

The optimal margin size in postoperative stereotactic radiosurgery (SRS) for brain metastases is unknown. Herein, the authors investigated the effect of SRS planning target volume (PTV) margin on local recurrence and symptomatic radiation necrosis postoperatively.

METHODS

Records of patients who received postoperative LINAC-based SRS for brain metastases between 2006 and 2016 were reviewed and stratified based on PTV margin size (1.0 or > 1.0 mm). Patients were treated using frameless and framed SRS techniques, and both single-fraction and hypofractionated dosing were used based on lesion size. Kaplan-Meier and cumulative incidence models were used to estimate survival and intracranial outcomes, respectively. Multivariate analyses were also performed.

RESULTS

A total of 133 patients with 139 cavities were identified; 36 patients (27.1%) and 35 lesions (25.2%) were in the 1.0-mm group, and 97 patients (72.9%) and 104 lesions (74.8%) were in the > 1.0–mm group. Patient characteristics were balanced, except the 1.0-mm cohort had a better Eastern Cooperative Group Performance Status (grade 0: 36.1% vs 19.6%), higher mean number of brain metastases (1.75 vs 1.31), lower prescription isodose line (80% vs 95%), and lower median single fraction–equivalent dose (15.0 vs 17.5 Gy) (all p < 0.05). The median survival and follow-up for all patients were 15.6 months and 17.7 months, respectively. No significant difference in local recurrence was noted between the cohorts. An increased 1-year rate of symptomatic radionecrosis was seen in the larger margin group (20.9% vs 6.0%, p = 0.028). On multivariate analyses, margin size > 1.0 mm was associated with an increased risk for symptomatic radionecrosis (HR 3.07, 95% CI 1.13–8.34; p = 0.028), while multifraction SRS emerged as a protective factor for symptomatic radionecrosis (HR 0.13, 95% CI 0.02–0.76; p = 0.023).

CONCLUSIONS

Expanding the PTV margin beyond 1.0 mm is not associated with improved local recurrence but appears to increase the risk of symptomatic radionecrosis after postoperative SRS.

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Stephen B. Tatter, Edward G. Shaw, Mark L. Rosenblum, Kastytis C. Karvelis, Lawrence Kleinberg, Jon Weingart, Jeffrey J. Olson, Ian R. Crocker, Steven Brem, James L. Pearlman, Joy D. Fisher, Kathryn A. Carson, Stuart A. Grossman and other members of The New Approaches to Brain Tumor Therapy Central Nervous System Consortium

Object. In this study the authors evaluated the safety and performance of the GliaSite Radiation Therapy System (RTS) in patients with recurrent malignant brain tumors who were undergoing tumor resection.

Methods. The GliaSite is an inflatable balloon catheter that is placed in the resection cavity at the time of tumor debulking. Low-dose-rate radiation is delivered with an aqueous solution of organically bound iodine-125 (Iotrex [sodium 3-(125I)-iodo-4-hydroxybenzenesulfonate]), which are temporarily introduced into the balloon portion of the device via a subcutaneous port. Adults with recurrent malignant glioma underwent resection and GliaSite implantation. One to 2 weeks later, the device was filled with Iotrex for 3 to 6 days, following which the device was explanted. Twenty-one patients with recurrent high-grade astrocytomas were enrolled in the study and received radiation therapy. There were two end points: 1) successful implantation and delivery of brachytherapy; and 2) safety of the device.

Implantation of the device, delivery of radiation, and the explantation procedure were well tolerated. At least 40 to 60 Gy was delivered to all tissues within the target volume. There were no serious adverse device-related events during brachytherapy. One patient had a pseudomeningocele, one patient had a wound infection, and three patients had meningitis (one bacterial, one chemical, and one aseptic). No symptomatic radiation necrosis was identified during 21.8 patient-years of follow up. The median survival of previously treated patients was 12.7 months (95% confidence interval 6.9–15.3 months).

Conclusions. The GliaSite RTS performs safely and efficiently. It delivers a readily quantifiable dose of radiation to tissue at the highest risk for tumor recurrence.

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Oral Presentations

2010 AANS Annual Meeting Philadelphia, Pennsylvania May 1–5, 2010