Current and potential application of GnRH agonists in gynecologic practice.

The development of GnRH-a (analogues or agonists) is a major leap forward in the treatment of various hormone-dependent diseases in medicine. Their introduction in reproductive endocrinology, in in vitro fertilization/embryo transfer (IVF/ET) and other assisted reproduction techniques had a revolutionary impact. They have been effective in other gynecologic conditions including fibroids, endometriosis, anovulatory disorders, precocious puberty, dysfunctional uterine bleeding, and operative hysteroscopy. Medical castration induced by GnRH-a has become first-line therapy in metastatic breast cancer. Their long-term use, though, has been associated with a variety of adverse effects such as bone loss and decreased cardioprotection. "Steroid add-back" therapy in these cases apparently is an effective alternative. It may allow their safe long-term application beyond 6 months, averting unpleasant side-effects and maintaining bone mass and cardioprotection.