Meningioma and hormonal influences.

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.