Long-term use of progestogens--effects on endometriosis, adenomyosis and myomas.

Oral progestins, without an estrogen component, have been reported to be effective in the treatment of endometriosis, but not adenomyosis or myomas. The mode of action on the target tissue is still a matter of debate. Besides the importance of estrogens for the development and growth of endometriosis and myomas, progesterone seems to play an important role in the modulation of mitotic activity, local growth factors and growth factor receptors, as well as other paracrine mechanisms. Earlier studies postulated activities via steroid receptor mechanisms, as observed in the uterine mucosa and myometrium. Recent studies, however, have raised some doubts about this hypothesis. Effective new therapies for endometriosis have been introduced during the last 30 years and progestins now have a place in the symptomatic management of pain, bleeding and other symptoms caused by endometriosis, adenomyosis or myoma, particularly when long-term medication is indicated or when repeated courses of treatment are acceptable.