Astrocytomas are brain tumors from glial cells, and they are classified by the World Health Organization WHO as astrocytoma, grade I or benign astrocytoma, grade II or malignant anaplastic astrocytoma, grade III and glioblastoma multiforme or grade IV. The high-grade gliomas have an incidence of . / , . The frequency of GBM is higher in men than in woman by a %. The survival of patients with GBM varied between and months, and less than % patients survive for years. The main treatments for GBM consist of surgical tumor resection, radiotherapy, and chemotherapy. These tumors present different endocrine characteristics, such as expression of aromatase enzyme, estrogen, progesterone, as well as testosterone receptors. In addition, patients with GBM produce estradiol in high concentrations when compared to those with low-grade astrocytomas. The highest mRNA expression of ER and aromatase in GBM patients had been postulated as prognostic biomarkers. The aromatase inhibitors had been used in the treatment of breast cancer in postmenopausal women with satisfactory results. At present time, several research groups are interested in testing these inhibitors for treating GBM.