Permanent I Interstitial Radiation Therapy in the Treatment of Non-GBM High-Grade Gliomas

This study evaluates prognostic factors influencing survival outcomes for 50 patients with permanent¹²⁵ iodine-125 implants in the primary treatment of non-GBM high-grade gliomas. Stereotactic treatment planning aimed to encompass the contrast-enhancing rim of the tumor visualized by CT, with an initial dose rate of 0.05 Gy/hour with ¹²⁵I, delivering 100 Gy at 1 year and 103.68 Gy at infinity. Survival was evaluated using the Kaplan–Meier method for unvariate analysis and the Cox regressional method for multivariate analysis. In addition to the implant, 31 patients received external radiation therapy (5000 to 6000 cGy) before the implant; 10 patients were implanted without additional external beam radiation, and 9 patients underwent external radiation therapy before implant placement. With a mean follow-up of 40.76 months (range 3.47–87 months); 1–, 3–, and 5-year survival were 78.5% (± .05%), 58.7% (± .07%), and 56.2% (± .07%) respectively. Since 56.2% of the patients were alive at 5 years, median survival has not been reached yet. Second surgery was performed following the implant in 19 patients. Findings were tumor recurrence in 11 patients (22.5%), radiation necrosis in 7 patients (14.3%), and brain abcess in 1 patient (2%). Age, sex, tumor location, side of brain, tumor volume, Karnofsky, and neurological status were correlated with survival outcome. Favorable prognostic factors were age younger than 45 years, superficial tumor location, and preoperative Karnofsky greater than 70. Surgical treatment of patients with non-GBM high grade gliomas combined with external beam radiation and permanent ¹²⁵I implants represent a valuable alternative for the treatment of patients with malignant gliomas, allowing patients good quality of life and long survival.