[Evaluation of 17-beta-hydroxysteroid dehydrogenase activity as a marker of the hormone dependence of breast cancers].

Intratumoral activity of the enzyme 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) was measured in 55 patients with breast cancer (17 pre- and 38 post-menopausal) before and/or after 8 days of a progestin treatment (lynestrenol 10 mg/day). In 12 patients the 17 beta-HSD ability to be stimulated was compared to estradiol and progesterone receptor (ER and PR) levels. In premenopausal patients 17 beta-HSD was higher when tumorectomy was performed in the luteal phase than in the follicular phase. In post-menopausal patients, 17 beta-HSD is higher after progestin treatment. However 17 beta-HSD stimulation by lynestrenol depends on receptor levels. It is most after markedly stimulated in ER+ PR+ tumors. It remains low in ER- PR- tumors. In conclusion, intratumoral measurement of the progesterone dependent enzyme (17 beta-HSD) in breast cancer after progestin treatment provides a fine and reliable index of the presence and functional character of PR and hormone dependence of the tumor.