Gamma Knife Stereotactic Radiosurgery for Radiation-induced Meningiomas

Background: Radiation-induced meningiomas present a unique clinical dilemma given the fact that patients with these tumors have often received a prior full course of radiotherapy. As such, traditional radiotherapy is limited by lifetime tissue tolerances to radiation, leaving surgery and radiosurgery as attractive treatment options.

Objectives: To ascertain the safety and efficacy of Gamma Knife radiosurgery as a treatment for radiation-induced meningiomas.

Methods: A retrospective chart review was conducted to identify patients who received Gamma Knife radiosurgery for a meningioma and met the criteria for this being a radiation-induced tumor. Serial imaging was used to determine the outcome of treatment and clinical notes used to assess for toxicity.

Results: We present our series of 12 patients with radiation-induced meningiomas treated with Gamma Knife stereotactic radiosurgery over a 12-year period at our institution. With a median follow-up of 35 months, local control was 100%. Two patients experienced distant brain failure (>2 cm from previous radiosurgical volume). Two patients experienced posttreatment toxicity related to treatment-related edema. A review of data collected from the scientific literature suggests that tumor volume predicts for treatment failure of radiosurgery.

Conclusions: Gamma Knife radiosurgery is both a safe and effective treatment for radiation-induced meningiomas.