Progestins and uterine leiomyoma.

Myomas are the most frequent benign gynecological tumors and are responsible for several symptoms and complaints. Their etiology is unknown and their pathology and proliferation is poorly understood. Besides the importance of estrogens for development and growth of the myoma, 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.