LONG-TERM RESULTS OF STEREOTAXIC BRACHYTHERAPY USED IN THE INITIAL TREATMENT OF PATIENTS WITH GLIOBLASTOMAS

Background. Despite optimal therapy with surgery and radiotherapy, the prognosis of patients with glioblastomas remains poor. Stereotactic b rachytherapy involves the accurate placement of radioactive isotopes w ithin brain tumors, significantly increasing the dose of radiation tha t can be delivered to the tumor bed without substantial risk to surrou nding normal tissue, potentially improving local tumor control and pat ient survival. Methods. Between February 1987 and July 1993, the autho rs treated 56 patients with glioblastomas with stereotactic brachyther apy as part of their initial therapy. Patients underwent surgery, limi ted field external beam radiotherapy, and brachytherapy with temporary high-activity iodine 125 sources, giving an additional 50 Gy to the t umor bed. Results. Median survival for patients undergoing brachythera py was 18 months compared with 11 months for a matched brachytherapy c ontrol group with similar clinical and radiologic features (P < 0.0007 ). Survival rates at 1, 2, and 3 years after diagnosis of 83%, 34%, an d 27%, respectively, for patients receiving brachytherapy were signifi cantly increased compared with survival rates of 40%, 12.5%, and 9%, r espectively, for control subjects. Thirty-six patients (64%) underwent reoperation for symptomatic radiation necrosis from 3 to 42 months (m edian, 11 months) after brachytherapy. The median survival of patients undergoing reoperation was 22 months compared with 13 months for thos e who did not have further surgery (P < 0.02). Thirty-five percent of patients relapsed locally within the brachytherapy target volume, wher eas 65% had marginal or distant relapses.