Meningiomas are slow-growing benign brain tumors. The etiology of meningioma is 
largely unknown, and exposure to high-dose ionizing radiation and coexistence 
with certain rare genetic conditions explain only a small fraction of the 
incidence of the disease. The evidence that implicates gender-specific hormones 
in the pathogenesis of meningioma emanates from data showing increased growth of 
meningiomas during pregnancy and change in size during menses. Observational 
data have identified the menopause and oophorectomy as conferring protection 
against the risk of developing meningiomas, while adiposity is positively 
associated with the disease. These tumors are also positively associated with 
breast cancer, although they express a different gonadal steroid receptor 
repertoire. About 70% of meningiomas express progesterone receptors, while fewer 
than 31% express estrogen receptors. These observations suggest that 
progesterone influences tumor growth. A progesterone antagonist such as 
mifepristone therefore may inhibit tumor growth. The use of hormone replacement 
therapy in symptomatic postmenopausal women either with previously treated 
disease or with dormant tumors is discussed, but remains controversial.