Plasma oestrogens in postmenopausal women with endometrial cancer.

Objective: To study plasma levels of estrogens and androgens, sex hormone-binding globulin (SHBG) and follicle stimulating hormone (FSH) in postmenopausal patients with endometrial cancer.

Design: Patients and controls were matched for age, body mass index, parity and years since menopause.

Setting: Department of Obstetrics and Gynaecology, Hvidovre Hospital, Denmark.

Subjects: Fifty postmenopausal patients with endometrial cancer and 54 matching controls.

Measurements: Plasma levels of SHBG, FSH, oestrone, oestradiol, oestrone-sulphate, dehydro-epiandrosterone sulphate, testosterone, and androstenedione were measured by radio-immunoassays. Free fractions of oestradiol and testosterone were calculated according to levels of SHBG and albumin.

Results: The levels of oestradiol, free oestradiol, and oestrone were elevated (P < 0.001) in patients compared with controls (oestradiol: 51 (45-59) vs 37 (34-41) pmol/l; free oestradiol: 0.69 (0.59-0.80) vs 0.48 (0.42-0.54) pmol/l; oestrone: 180 (159-204) vs 119 (107-133) pmol/l (mean values (95% CI) in patients vs controls)). Furthermore, an increased oestrone:androstenedione ratio (0.095 vs 0.072, P < 0.01) was found in patients. SHBG correlated negatively (P < 0.001) with body mass, while the free fractions of oestradiol and testosterone correlated positively (P < 0.01) with body mass, in both patients and controls. Multiple regression analysis showed that the differences in oestrogen levels between the two groups persisted when controlling for the effect of body mass, age, years since menopause, parity, and levels of SHBG and FSH.

Conclusion: Patients with endometrial cancer exhibit increased plasma levels of oestradiol and oestrone. Speculatively, these oestrogens may result from an increased oestrone conversion from androstenedione, an increased ovarian and adrenal secretion of androstenedione, or alternative oestrogen production routes. The present findings support the hypothetical role for oestrogens in the aetiology of endometrial cancer.