Despite a high effort in the research of malignant brain tumors, the clinical 
results in treatment of malignant brain tumors are still very poor. Brain tumors 
are a major cause of morbidity and mortality in the population. New primary 
brain tumors develop in 2-4 of 100,000 adults each year (1). Recent evidence 
indicates that the prevalence of primary brain tumors is increasing, especially 
in the elderly (2). The astroglial brain tumors, including the highly malignant 
glioblastoma multiforme (GBM), are the most common primary brain tumors. For 
these tumors, the first line of treatment is surgery and almost always 
radiotherapy as an adjuvant. A variety of patient-management strategies are 
currently used for GBM, from supportive care to aggressive multimodality 
approaches. The principal reason for this wide spectrum of approaches is that, 
despite aggressive therapy, which includes surgical removal of the tumor, 
postoperative high-dose radiation (60 gy), chemotherapy, and other adjuvant 
treatments, the prognosis of patients with GBM is very poor (3 -6). In a series 
of NCOG protocols on glioblastoma multiforme patients with Karnofsky performance 
scores of 60 or higher, who were treated with postsurgical radiation therapy and 
adjuvant chemotherapy with nitrosourea-based drug combinations, the median 
survival and time of tumor progression were consistently above 50 and 34 wk, 
respectively (7 -9). The nitrosoureas (BCNU and CCNU), alone and in combination, 
are the most active cytotoxic drugs for recurrent and progressive tumors, 
although most of these responses are transient and in patients with 
well-differentiated gliomas. When glioblastoma multiforme recurs, which happens 
in nearly 100% of all cases, however, the median survival from the start of 
treatment is about 6 mo, with only 22% of patients surviving longer than 1 yr 
(11). Therefore, there is a great interest in local treatment modalities. A 
wafer impregnated with carmustine, for use as an implant after surgical removal 
of recurrent GBM showed a prolongation in the median survival time of only 2 mo, 
from 20 to 28 wk in a study with a total of 222 patients. In another study, a 
median survival of 9 mo was found in a selected group of patients with recurrent 
GBM who underwent a second operation, but a reasonable quality of life in those 
patients was limited to 10 wk (12).