Abstract
IntroductionChanges in sex hormones with weight loss might have implications for breast cancer prevention but have not been examined extensively, particularly in African-American (AA) women.MethodsWe conducted a prospective study of 278 overweight/obese postmenopausal women (38% AA) not taking hormone therapy within the Weight Loss Maintenance Trial. All participants lost at least 4 kg after a 6-month weight-loss phase and attempted to maintain weight loss during the subsequent 12 months. We evaluated the percentage changes in estrone, estradiol, free estradiol, testosterone, free testosterone, androstenedione, dehydroepiandrosterone sulfate and sex hormone-binding globulin (SHBG) using generalized estimating equations.ResultsIn all study phases, AA women had higher levels of estrogen and testosterone concentrations, independent of adiposity. On average, participants lost 7.7 kg during the weight-loss phase, and concentrations of estrone (-5.7%, P = 0.006), estradiol (-9.9%, P <0.001), free estradiol (-13.4%, P <0.0001), and free testosterone (-9.9%, P <0.0001) decreased, while the SHBG concentration (16.2%, P <0.001) increased. Weight change did not significantly affect total testosterone or other androgen concentrations. Compared with non-AA women, AA women experienced less change in estrogens per kilogram of weight change (that is, per 1 kg weight loss: estrone, -0.6% vs. -1.2%, P-interaction = 0.10; estradiol, -1.1% vs. -1.9%, P-interaction = 0.04; SHBG, 0.9% vs. 1.6%, P-interaction = 0.006; free estradiol, -1.4% vs. -2.1%, P-interaction = 0.01).ConclusionTo the best of our knowledge this is the first study to examine and compare the effects of intentional weight loss and maintenance on a panel of sex hormones in AA women and non-AA women. Although speculative, these data suggest hormonal differences may contribute to different racial patterns of breast cancer incidence and mortality and encourage further investigations to understand the long-term effects of weight loss on sex hormones in obese postmenopausal women.Trial RegistrationClinicalTrials.gov: NCT00054925
Highlights
Changes in sex hormones with weight loss might have implications for breast cancer prevention but have not been examined extensively, in African-American (AA) women
None of these studies have included a substantial number of African-American (AA) women, a population that has a greater prevalence of obesity [21], unique incidence patterns of hormone-receptor-defined breast cancer subtypes [22], and higher breast cancer mortality when compared with Caucasian women
Compared with non-AA women, AA women experienced less change in hormone per kilogram of weight lost, with estrone declining 0.6% versus 1.2% (Pinteraction = 0.10), estradiol declining 1.1% versus 1.9% (P-interaction = 0.04), and free estradiol declining 1.4% versus 2.1% (P-interaction = 0.01), while sex hormone-binding globulin (SHBG) increased less (0.9% vs. 1.6%, P-interaction = 0.006)
Summary
Changes in sex hormones with weight loss might have implications for breast cancer prevention but have not been examined extensively, in African-American (AA) women. To the best of our knowledge, only one recent adequately powered clinical trial has examined the direct effects of weight loss on sex hormones [20] and none have examined weight loss maintenance None of these studies have included a substantial number of African-American (AA) women, a population that has a greater prevalence of obesity [21], unique incidence patterns of hormone-receptor-defined breast cancer subtypes [22], and higher breast cancer mortality when compared with Caucasian women. A better understanding of the long-term effects of weight loss on endogenous sex hormones in obese postmenopausal women may provide clues to the racial differences in breast cancer incidence and prognosis, and might have major implications for prevention
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