# Reirradiation of Large or Multifocal High-Grade Gliomas With Gyroscopic Radiosurgery in Combination With Modulated Electro-Hyperthermia

## TL;DR

This study explores using gyroscopic radiosurgery and modulated electro-hyperthermia to treat recurring high-grade brain tumors, showing improved survival and low toxicity.

## Contribution

The novel use of gyroscopic radiosurgery combined with modulated electro-hyperthermia for reirradiation of high-grade gliomas is evaluated.

## Key findings

- The combination therapy achieved a 58.3% six-month survival rate with no in-field recurrences.
- Acute toxicity was low, with manageable side effects observed in most patients.

## Abstract

Introduction: High-grade gliomas (HGGs) are the most common primary malignant brain neoplasms in adults, with a high rate of local relapse in the first two years after primary treatment, resulting in poor prognosis. The aim of this study is to describe the potential benefits of the implementation of gyroscopic radiosurgery (GRS) in combination with modulated electro-hyperthermia (mEHT) as a radiosensitizer for the reirradiation of large or multifocal recurrent HGGs.

Methods: A study was designed to evaluate the impact of survival and clinical tolerance. Clinical information of 15 patients treated between April 2023 and September 2024 was analyzed.

Results: Fifteen patients with a median age of 50 years and grade 4 (n = 13) or grade 3 (n = 2) gliomas were included in the study. The median Karnofsky Performance Status (KPS) was 70. Multifocal disease was present in 10 patients. The median time from previous radiation was 16 months. Twelve patients were eligible for analysis. The median planning target volume (PTV) was 33.6 cc; 48% (10 lesions) received five fractions (20-30 Gy), 38% (eight lesions) received one fraction (15-18 Gy), and 14% (three lesions) received three fractions (24 Gy). mEHT was applied every 48 hours. The median follow-up was seven months with no in-field recurrences reported. Actuarial overall survival (OS) from GRS and mEHT was 58.3% at six months and 25% at 12 months. Acute tolerance was acceptable, with 33.3% of patients showing improvement, 33.3% remaining stable, and 33.3% presenting grade 2 radiation necrosis, managed with outpatient steroid adjustment.

Conclusions: High-risk, HGG reirradiation with GRS and mEHT showed a favorable impact on local control and OS with low toxicity. Longer follow-up and larger series are needed to validate these results.