Hormonal regulation of endometriosis and the rationales and effects of gonadotrophin-releasing hormone agonist treatment: a review.

The knowledge about the role of oestrogen in the regulation of endometriosis growth and symptoms has been reviewed. Studies on oestrogen and progesterone metabolism and receptivity in endometriotic tissue and the impact on growth regulation and clinical symptoms of steroidal hormones are discussed. These include tissue sample assays, ex-vivo tissue culturing as well as clinical studies concerning the effect of different hormonal treatment. All studies published on steroid receptors in endometriotic tissue have shown lower levels of oestrogen and progesterone receptors in endometriotic tissue than in uterine endometrium. These data might, at least partly, explain the poor clinical response to hormonal treatment experienced in some cases. However, in cases of hormone-sensitive endometriotic tissue, a complete ovarian inactivation is not important, as comparable reducing effects on lesions and symptoms are seen after various hormonal treatments leading to a varying degree of ovarian inactivation. A less pronounced hypo-oestrogenism during treatment gives less severe consequences for the future, mainly concerning the bone mass and the circulation, and might allow a prolonged symptom-free period on low-dose treatment when needed. Not all cases of endometriosis are receptive to hormonal treatment.