Interstitial irradiation of malignant gliomas

Beginning in 1986, using software to optimize radiation dosimetry, we have stereotactically placed removable catheters containing high activity I-125 sources into malignant gliomas in 56 patients. There were 32 men and 24 women, age 7 to 73. Forty-four had glioblastoma multiforme, and 12 anaplastic astrocytoma. Mean Karnofsky performance score was 75, range 50-100. Twenty patients (all with glioblastoma) were implanted after resection before further therapy, and 36 were implanted at recurrence following resection, external irradiation and chemotherapy. Six thousand cGy was delivered to the enhancing tumor contour on CT scan. Mean dose rate was 37 cGy/hr. Mean tumor volume was 41 cc, range 5-187 cc. Mean volume of brain that received 60 cGy was 67 cc, range 11-184 cc. Of 20 patients treated after resection alone, 8 are alive, 3-43 months after implantation; median survival is 22 months. Of 36 patients treated at recurrence, 14 are alive, 0-19 months after implantation; median survival is 10 months. The most common side effect of the procedure, which occurred in five patients, was catheter misplacement. Twenty-four patients (43%) required 27 reoperations, 1-25 months after implantation. In 25 pathologic specimens available for review, microscopic tumor foci with substantial radiation necrosis were found in 18, radiation necrosis only was noted in 5, and glioma alone was seen in 2.