Aromatase Inhibitors for Endometriosis-Associated\nInfertility; Do We Have Sufficient Evidence?

Orally active aromatase inhibitors (AIs) have gained attention for treatment of infertile\nwomen with endometriosis in whom aromatase p450 is aberrantly expressed. This review\naimed to critically appraise and summarize the available evidence concerning the use of\nAIs for management of endometriosis-associated infertility. PubMed was searched to May\n2015 with the following key words: endometriosis, infertility and aromatase. Priority was\ngiven for randomized controlled trials (RCTs) followed by other study designs. Main outcome measures were as follows: rates of clinical pregnancy, miscarriage and live birth as\nwell as endocrine outcomes. Eighty-two abstracts were screened and six original articles\nwere included. A RCT demonstrated that post-operative letrozole treatment did not improve\nspontaneous pregnancy rate. Another RCT reported no superiority of letrozole superovulation over clomiphene citrate (each combined with intrauterine insemination) in minimalmild endometriosis and previous laparoscopic treatment. Anastrozole significantly inhibited the growth of endometriotic cells and their estrogen production in culture. In assisted\nreproductive technology (ART) cycles, dual suppression (Agonist/anastrozole) was tested\nin a pilot study with a pregnancy rate of 45% however, high pregnancy loss (30%) occurred. A retrospective study showed that letrozole may improve endometrial receptivity\nin endometriotic patients undergoing in vitro fertilization (IVF). An opposite view from\nan in vitro study showed lower estradiol production and aromatase expression in cultured\ngranulosa cells from endometriotic women undergoing IVF and marked reduction under\nletrozole. In conclusion, current evidence is limited. More trials are warranted to enhance\nour knowledge and provide a clear and unequivocal evidence to guide our clinical management of infertile women with endometriosis using AIs.