Patterns of Sex Steroid Hormones in Nipple Aspirate Fluid during the Menstrual Cycle and after Menopause in Relation to Serum Concentrations

Abstract

Previous studies have shown that progesterone concentrations in serum and nipple aspirate fluid (NAF) are significantly correlated in premenopausal women, but estradiol concentrations are not. We therefore sought to ascertain the patterns of both steroids in NAF throughout the menstrual cycle and in postmenopausal women. Simultaneous samples of blood and NAF were obtained from 40 premenopausal and 16 postmenopausal women. Premenopausal samples were backdated from the following menstrual period. Steroids were purified by high-performance liquid chromatography before quantification by immunoassays. Serum steroids and NAF progesterone followed the expected pattern across the menstrual cycle, with a midcycle peak of estradiol and a midluteal peak of progesterone. However, the estradiol peak in NAF occurred about a week after the serum peak in the midluteal phase, when serum estradiol had declined to less than half the value at midcycle. NAF estrone was also elevated at the midluteal phase. Potential estrogen precursors androstenedione, estrone sulfate, and dehydroepiandrosterone sulfate declined in NAF from midcycle to the midluteal phase as NAF estradiol was increasing. Progesterone concentrations were significantly lower in NAF in postmenopausal women than in premenopausal women, but estrogen concentrations were not. This is the first description of the temporal relationships of sex steroids in NAF and serum relative to the menstrual cycle. These results provide insights into the lack of correlation of NAF and breast tissue estrogens with serum estrogens, and generate new hypotheses. Cancer Epidemiol Biomarkers Prev; 19(1); 275-9.

Methodological considerations in estrogen assays of breast fluid and breast tissue

“…We found a correlation of 0.29 with NAF [7]; Maskarinec et al [18] found r = 0.37. In addition to the obvious fluctuations of serum estradiol, we found that NAF estradiol had a pattern during the menstrual cycle that was different from that in serum [12].…”

“…The lipid residue from the NAF and DLF samples was extracted into ethyl acetate-hexane (3:2). The estrogens were either separated by the alkaline partition method [9] or by HPLC [12]. In the solvent partition method estradiol is extracted from the NAF or concentrated DLF samples into ethyl acetate-hexane (3:2) and, after evaporation of the solvent, the residue is partitioned between 0.4 N aq.…”

“…A gradient was started at 40 min to a final concentration of 71% of the acetonitrile-methanol solvent at 50 min [12]. In this case, the fractions containing estradiol, estrone, and other steroids are collected separately, the solvent is evaporated, and the residue is dissolved in the assay buffer for radioimmunoassay.…”

Soy Isoflavones for Breast Cancer Risk Reduction—Response

“…When results in the present study are compared with our previous publications, it is true that estradiol concentrations in NAF have been consistently, but not significantly, lower in postmenopausal women than in premenopausal women. The number of postmenopausal subjects in our 2010 and 2004 publications was 18 in each (1,2). The higher postmenopausal NAF estradiol concentrations in the present study (3), although unexpected, can be attributed to chance when the sample size is small, as it was here, with 8 NAF-yielding postmenopausal subjects in the soy group.…”

Prediction of menopausal status from estrogen-related gene expression in benign breast tissue

“…Demographic information of subjects used for analysis from both studies was summarized in Table 1. The true menopausal status (TMS) was determined using last menstrual period (LMP) date, plasma estradiol (E2), progesterone (P4), and follicle-stimulating hormone (FSH) concentrations, measured by radioimmunoassay, and enzyme immunoassay as described previously [7]. Hormonal criteria for TMS classification were FSH [ 30 mIU/ ml, and E2 \ 30 pg/ml, P4 \ 3 ng/ml.…”