ALCOHOL, HEIGHT, AND ADIPOSITY IN RELATION TO ESTROGEN AND PROLACTIN LEVELS IN POSTMENOPAUSAL WOMEN

Background: Alcohol use, height, and postmenopausal adiposity have eac h been positively associated with postmenopausal breast cancer risk in most epidemiologic studies, The mechanism underlying these associatio ns is unclear, although an effect of these factors on hormone levels h as been hypothesized, Few previous studies have evaluated the relation ship of either alcohol consumption or height with plasma hormone level s, A positive association between adiposity and plasma estrogen levels in postmenopausal women has been reported consistently, Purpose: Usin g archived frozen plasma samples and corresponding data from participa nts in the Nurses' Health Study, we determined plasma hormone levels a nd assessed these levels in relation to alcohol consumption, height, a nd adiposity among postmenopausal women, Methods: Blood samples were c ollected from a subset of participants in the Nurses' Health Study in 1989 and 1990, then stored in liquid nitrogen, Hormone concentrations in 217 archived plasma samples (from healthy postmenopausal women) wer e analyzed in 1993, Spearman correlation coefficients were calculated to assess the linear association between alcohol consumption during th e previous year (mean daily intake in grams per day ascertained from s emiquantitative food-frequency questionnaires completed in 1990 or 199 1), height, and adiposity (as measured by body mass index [BMI] in kg/ m(2), with weight reported at time of blood collection), and plasma ho rmone levels, Two-sided P values were also calculated, Results: After controlling for age, height, smoking status, and BMI, alcohol consumpt ion was positively associated with estrone sulfate concentrations (r = .17; P = .02); no statistically significant association was noted for the other plasma hormones measured, Mean plasma estrone sulfate level s were 159 pg/mL in women who reported no alcohol use versus 211 pg/mL in women consuming 30 g or more of alcohol per day, After adjusting f or the other covariates, we observed a strong positive correlation bet ween BMI and plasma estrogens (r ranging from .37 for estrone and estr one sulfate to .63 for bioavailable estradiol, with all P values less than or equal to.01; prolactin was the only hormone unassociated with BMI, r = -.01). Height was unrelated to either plasma estrogens or pro lactin, Conclusions: BMI and alcohol use were positively associated wi th postmenopausal plasma estrogen and estrone sulfate levels, respecti vely, Implications: The association of alcohol consumption and postmen opausal obesity with subsequent breast cancer risk might be mediated, at least in part, through an influence on postmenopausal plasma estrog en levels, Additional studies are needed to further quantify the relat ionship between alcohol consumption and plasma hormone levels and to e lucidate the physiologic basis for this association.