Effect of adjuvant iridium-192 brachytherapy on the survival of patients with malignant gliomas.

The effect of iridium-192 brachytherapy (BRTX) on the survival of patients with malignant gliomas was evaluated in 83 patients with malignant gliomas (42 astrocytoma grade III, 41 glioblastoma multiforme) over a period of 8.5 years. Fifty patients (Group 1) received only standard external beam radiotherapy (EBRT) (mean dose 51.5 +/- 12.4 Gy in 2.0 Gy fractions), and 33 patients (Group 2) received EBRT (mean dose 51.0 +/- 10.8 Gy) combined with BRTX (mean dose 50.2 +/- 13.2 Gy, dose rate of 0.3-0.4 Gy/hr). The median survival periods for patients in Groups 1 and 2 were 12.2 and 23.7 months, respectively (p = 0.0145). The median survival for 17 patients in Group 2 with glioblastoma multiforme was 21.9 months. Using BRTX as an adjuvant to EBRT appeared to confer survival benefits compared to only EBRT (p = 0.0284). Univariate and multivariate analysis identified the variables of histological diagnosis, location, Karnofsky performance status, and BRTX as relevant risk factors for survival time (p < 0.05 for each factor). Among these factors, BRTX was the most important for prolonging survival (p = 0.0015). Adjuvant iridium-192 BRTX and conventional EBRT appears to greatly improve the survival time of patients with malignant gliomas compared to only EBRT and may be the treatment of choice in selected patients with tumors located in deep-seated or eloquent areas.