Treatment of malignant gliomas with interstitial irradiation and hyperthermia
ABSTRACT
A Phase I study of interstitial thermoradiotherapy for high-grade supratentorial gliomas has been completed. The objective of this trial was to test the feasibility and toxicity of hyperthermia induced by ferromagnetic implants in the treatment of intracranial tumors. The patient population consisted of 16 males and 12 females, with a median age of 44 years and a median Karnofsky score of 90. Nine patients had anaplastic astrocytoma while 19 had glioblastoma multiforme. Twenty two patients were treated at the time of their initial diagnosis with a course of external beam radiotherapy (median dose 48.4 Gy) followed by an interstitial implant with Ir-192 (median dose 32.7 Gy). Six patients with recurrent tumors received only an interstitial implant (median dose 40 Gy). Median implant volume for all patients was 55.8 cc and median number of treatment catheters implanted per tumor was eighteen. A 60-minute hyperthermia treatment was given through these catheters just before and right after completion of brachytherapy. Time-averaged temperatures of all treatments were computed for sensors located within the core of (> 5 mm from edge of implant), and at the periphery of the implant (outer 5 mm). The percentage of sensors achieving an average temperature > 42 degrees C was 61% and 35%, respectively. Hyperthermia was generally well tolerated; however, there have been 11 minor toxicities, which resolved with conservative management, and one episode of massive edema resulting in the death of a patient. In addition, there were three major complications associated with the surgical implantation of the catheters. Preliminary survival analysis shows that 16 of the 28 patients have died, with a median survival of 20.6 months from diagnosis. We conclude that interstitial hyperthermia of brain tumors with ferromagnetic implants is feasible and carries significant but acceptable morbidity given the extremely poor prognosis of this patient population.