The emerging use of aromatase inhibitors for endometriosis treatment

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The emerging use of aromatase inhibitors for endometriosis treatment Warren B Nothnick

Abstract Endometriosis is defined as the growth of endometrial tissue outside of the uterine cavity. The disease occurs primarily in women of reproductive age but recurrent endometriosis is also detected in post-menopausal women. Regardless of age, endometriosis is associated with pain and reduces the quality of life for millions of women world-wide. Conventional therapies focus on reducing systemic levels of estrogen which results in cessation of endometriotic implant growth and pain symptoms associated with the disease. However, these treatments are not effective in all women and are not without side effects. Based upon the discovery that endometriotic tissue overexpresses aromatase, an enzyme critical for estrogen production, emphasis has been placed upon the use of aromatase inhibitors for the treatment of endometriosis and its associated symptoms. This article will review the rationale behind the use of aromatase inhibitors in treating endometriosis and summarize those studies which have evaluated the use of aromatase inhibitors in the treatment of endometriosis and its associated symptoms. Review Aromatase and estrogen biosynthesis

Estradiol 17b (or estrogen) is the major biochemical driving force for endometriotic implant growth. In women of reproductive age, estrogen is derived primarily from the ovaries and the notion that systemic estrogen drives implant growth has long been considered dogma. However, substantial evidence also points to the endometriotic implant as an intracrine source of estrogen. This locally produced estrogen results from overexpression of P450 aromatase (referred to hence forth as aromatase) by endometriotic tissue (Figure 1). As a result, considerable emphasis has been placed upon the use of aromatase inhibitors to curtail endometriotic implant production of estrogen and subsequent implant growth. The following review highlights the discovery of endometriotic aromatase expression and the use of aromatase inhibitors in the treatment of endometriosis. Aromatase expression in endometriotic tissue

The first report describing expression of aromatase in peritoneal endometriotic implants was published in 1996 by Noble and colleagues [1]. Since this initial Correspondence: [email protected] Departments of Obstetrics and Gynecology and Molecular and Integrative Physiology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA

report, numerous independent investigators have described the expression and cellular localization of aromatase transcript and protein in endometriotic tissue [2-8] as well as eutopic endometrium from women with the disease [2,3,5,8-13]. The majority of these studies demonstrate that aromatase mRNA can be detected in most but not all endometriotic biopsies or eutopic endometrial biopsies from women with endometriosis; however, none of the endometrial biopsies from women without endometriosis expressed aromatase transcript. With