Breast cyst fluid concentrations of beta-endorphin, steroids and gonadotrophins in premenopausal women with gross cystic disease.

Breast cyst fluid (BCF) and plasma levels of beta-endorphin (beta-EP), oestradiol (E2), progesterone (P), luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyroid-stimulating hormone (TSH), prolactin (PRL) and cortisol were assayed radiochemically in a group of 10 premenopausal women aged 45-50 years suffering from gross cystic breast disease. The concentration of beta-EP (fmol/ml) in BCF (17.6 +/- 4.6 S.E.) was over four times higher than that in plasma (4.2 +/- 0.5 S.E.). The level of E2 was 41 times higher (1738.2 +/- 350.5 S.E. pg/ml) and that of P was 47 times higher (65.47 +/- 8.25 S.E. ng/ml) in BCF than in plasma. The significantly increased values of beta-EP, E2 and P in BCF and the identification of beta-EP in the cyst-lining epithelium indicated that local synthesis occurs. Growth factor-like properties of beta-EP and E2 are responsible for the propagation of cystic changes. The autonomous formation and activity of beta-EP, E2 and P in cystic formations were not correlated with LH, FSH, TSH and cortisol levels, which were significantly higher in plasma than in BCF. The concentration of PRL in BCF was not significantly higher than that in plasma. Moreover, the plasma concentrations of testosterone, androstenedione, thyroxine, triiodothyronine, thyroxine-binding globulin and sex-hormone-binding globulin were within the normal ranges. In this study we demonstrated synergism between beta-EP and steroid hormones which encourages the development of gross cystic disease in premenopausal women.