Estrogen and progestin receptor levels in uterine leiomyomata: relation to the tumour histology and the phase of menstrual cycle.

Estrogen receptor (ER) and progestin receptor (PR) levels in the myometria and uterine leiomyomata of 26 normally menstruating women were studied. No significant menstrual cycle-related change in ER level was found in the leiomyomata or normal myometria. The ER levels in normal myometria and in cellular leiomyomata, but not in usual leiomyomata, tended to be higher in the follicular phase than in the luteal one. The "cytosolic" PR levels in cellular leiomyomata and in usual leiomyomata with no or with slight hyalinization as well as in their parental myometria were significantly lower in the luteal than in the follicular phase. This was not the case in usual leiomyomata with more intense hyalinization. The findings show that the reactivity of uterine leiomyomata to estrogens and/or progestins may be related to the histological features of the tumors. This should be realized when studying the steroid receptor levels in the tumours and possibly also when planning an endocrine therapy for the leiomyomata.