equilin and Uterine-Neoplasms

Topics: Animals; Cholesterol; Equilin; Estradiol; Estrogens; Estrone; Female; Horses; Humans; Menopause; Pregnancy; Receptors, Estrogen; Uterine Neoplasms

Two groups of postmenopausal women were seen at monthly intervals during a 6-month trial of cyclic therapy with conjugated equine oestrogens ('Premarin'). the seven women in the first group were taking premarin alone and the six women in the second group were taking premarin plus a progestagen, norethisterone acetate. On each visit, serum unconjugated oestrogens were measured by radioimmunoassay. Mean concentrations for the first group were 393 (+/- 203, SD) pmol/l for 17 beta-oestradiol, 599 (+/- 180) pmol/l for oestrone, and 6840 (+/- 5130) pmol/l for equilin. Corresponding levels for the second group were 342 (+/- 112) pmol/l, 564 (+/- 279) pmol/l, and 8840 (+/- 4020) pmol/l. 3 months after completion of therapy, the oestrone and 17 beta-oestradiol concentrations had returned to pre-treatment levels in both groups, but equilin was detected in 3 out of 3 women in the first group at a mean level of 532 (+/- 267) pmol/l and in 2 out of 4 women in the second group at 1170 (+/- 870) pmol/l. In view of the prolonged presence of equilin and the possible association between treatment with conjugated equine oestrogens and endometrial cancer, it is suggested that equilin-containing compounds should not be given for more than 12 months.

Topics: 17-Ketosteroids; Castration; Equilin; Estradiol; Estrogens, Conjugated (USP); Estrone; Female; Humans; Menopause; Middle Aged; Norethindrone; Postoperative Care; Time Factors; Uterine Neoplasms

One of the main components of conjugated equine estrogens is equilin sulfate and this estrogen in postmenopausal women is metabolized to 17 beta-dihydroequilin, 17 beta-dihydroequilenin and equilenin. To investigate the possibility that some of these estrogens may be formed directly in the target tissues, we studied the in vitro metabolism of [3H]equilin in various types of normal and malignant human endometrium, including adenocarcinoma grown in athymic nude mice. The results indicate that normal and neoplastic human endometrium can form the above three metabolites. The highest level of 17 beta-reduced products were isolated from the normal secretory endometrium. Equilenin was the most abundant metabolite isolated from both the normal and malignant endometrium. The formation of [3H]equilenin indicates the presence of a 6,8(9) steroid dehydrogenase-isomerase in the human endometrium. The formation of 17 beta-dihydroequilin in the endometrium may be of importance as this estrogen is 8 times more potent as a uterotrophic agent than equilin and estrone.

Topics: Adenocarcinoma; Animals; Endometrium; Equilin; Female; Humans; Mice; Mice, Nude; Neoplasm Transplantation; Uterine Neoplasms