Sex Hormone Levels in Premenopausal African-American Women With Upper and Lower Body Fat Phenotypes

Abstract

Body fat distribution may be a better marker of a hormonal pattern associated with increased breast cancer risk than obesity. This cross-sectional study of 106 healthy premenopausal African-American (AA) women compared the midfollicular phase sex hormone and sex hormone-binding globulin levels in upper body fat (UBF) and lower body fat (LBF) phenotype and obese and nonobese women. Multivariate regression analyses were used to control for various confounders, including dietary factors. UBF phenotype women had 37% (P = 0.02), 50% (P = 0.01), 52% (P = 0.007), and 50% (P = 0.009) higher levels of estradiol (E2), free E2, testosterone (T), and free T, respectively, than LBF phenotype women. Only %free T was higher in obese than in nonobese women (P = 0.02). The levels of E2, free E2, %free E2, T, and free T were higher [by 42% (P = 0.01), 68% (P = 0.001), 18% (P = 0.04), 36% (P = 0.04), and 61% (P = 0.01), respectively] and the level of sex hormone-binding globulin was lower [by 28% (P = 0.04)] in obese UBF than in nonobese LBF phenotype women. These findings support the hypothesis that body fat distribution may be a better marker of a hormonal pattern associated with increased breast cancer risk than obesity. Obese UBF phenotype AA women, in particular, have a high-risk hormonal profile. Future breast cancer studies might consider controlling for measures of obesity and body fat distribution to minimize confounding.