Medical Therapies: Aromatase Inhibitors

Approximately half of women with endometriosis achieve pain relief from existing medical or surgical treatments. Medical treatments are usually directed at inhibiting estrogen action or its production from the ovaries and do not address local estrogen biosynthesis by the aromatase enzyme in endometriotic lesions. A single gene encodes aromatase, which is the final enzyme in the estrogen biosynthesis pathway, and its inhibition effectively eliminates estrogen production. Recent pilot studies have shown that treatment with an aromatase inhibitor reduced lesion size and pelvic pain. In premenopausal women, an aromatase inhibitor alone may induce ovarian folliculogenesis and thus is combined with a progestin, an oral contraceptive, or a gonadotropin releasing hormone agonist. The side-effect profile of aromatase inhibitors administered in combination with an oral contraceptive or a progestin is remarkably well tolerated. Aromatase inhibitors represent a new class of medications with significant potential for the treatment of endometriosis.