Cs-131 brachytherapy for patients with recurrent glioblastoma combined with bevacizumab avoids radiation necrosis while maintaining local control

Brachytherapy. Sep-Oct 2020;19(5):705-712. doi: 10.1016/j.brachy.2020.06.013.

Abstract

Purpose: Re-irradiation of recurrent glioblastoma (GBM) may delay further recurrence but re-irradiation increases the risk of radionecrosis (RN). Salvage therapy should focus on balancing local control (LC) and toxicity. We report the results of using intraoperative Cesium-131 (Cs-131) brachytherapy for recurrent GBM in a population of patients who also received bevacizumab.

Methods and materials: Twenty patients with recurrent GBM underwent maximally safe neurosurgical resection with Cs-131 brachytherapy between 2010 and 2015. Eighty Gy was prescribed to 0.5 cm from the surface of the resection cavity. All patients previously received adjuvant radiotherapy and temozolomide, and received bevacizumab before or after salvage brachytherapy. Seven of 20 (35%) tumors were multiply recurrent and had been previously salvaged with external beam radiotherapy. Patients received MRI scans every 2 months monitored for recurrence, progression, and RN.

Results: Median tumor diameter was 4.65 cm (range, 1.2-6.3 cm). Median number of seeds pace was 41 (range, 20-74) with total seed activity 96.8U (range, 41.08-201.3U). At a median followup of 19 months, crude LC was 85% and median overall survival was 9 months (range, 5-26 months). There were two postoperative wound infections (10%), three seizures (15%), and 0% incidence of RN.

Conclusions: Our study demonstrates that while LC and survival are similar to other studies of postoperative external beam radiotherapy, no RN occurred in any of these patients, including 7 multiply re-irradiated patients. Of interest, there were patients with multiple recurrences whose survival extended beyond 20 months. These findings suggest that the use of highly conformal Cs-131 brachytherapy is a promising treatment for patients with recurrent GBM with minimal risk of development of RN.

Keywords: Avastin; Bevacizumab; Brachytherapy; Cesium-131 (Cs-131); Glioblastoma; Glioblastoma multiforme; High-grade glioma; Radiation necrosis.