Aromatase inhibitors in the treatment of endometriosis

In the last ten years, it has been demonstrated that aromatase P450, a key enzyme for estrogens biosynthesis, may have a pathogenic role in endometriosis because it is aberrantly expressed in endometriotic implants and in eutopic endometrium of women with endometriosis. Therefore, inhibition of aromatase activity may represent a new therapeutic option for endometriosis. Several case reports and pilot studies proposed the use of aromatase inhibitors in the treatment of pain symptoms caused by endometriosis both in women of reproductive age and in menopausal patients. When aromatase inhibitors are administered to women of reproductive age, the reduction of estrogens production increases gonadotropin secretion causing stimulatory effects on the ovary; therefore, in premenopausal women, aromatase inhibitors must be combined with additional drugs that effectively down-regulate the ovaries (such as progestins or oral contraceptive pill). Case reports and observational studies have shown that pain symptoms caused by endometriosis quickly improve after administration of aromatase inhibitors. Limited data are available on the long-term course of pain symptoms after completion of treatment with aromatase inhibitors; however, recent studies suggest that symptoms may recur at short-term follow-up. Contradictory results have been reported on the effects of aromatase inhibitors on endometriotic lesions, with some authors describing disappearance and other authors reporting persistence of pelvic nodules after treatment. Further research in the form of randomized controlled trials is required before recommending the routine use of aromatase inhibitors in endometriosis.