MAMMOGRAPHIC DENSITY AND SOY ISOFLAVONES

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。背景：食用大量大豆的人群，如在许多亚洲国家，与食用典型西方饮食的人群相比，卵巢激素水平较低，乳腺癌发病率较低，乳房x光检查密度也较低。我们的临床研究发现，当绝经前妇女食用含有弱雌激素异黄酮的豆浆提供15%的能量时，她们的卵巢激素水平最低。未观察到不良反应。进一步的问题是异黄酮是否是影响乳腺癌风险的关键成分，以及它们是否通过影响乳腺癌的其他可逆风险标志（如乳腺密度）来做到这一点。目的：我们建议对200名绝经前妇女（N=100/组）进行一项随机、双盲、安慰剂对照的两组研究：(1)确定持续暴露于大豆异黄酮对卵巢激素、乳腺密度和骨密度的血清水平的影响；(2)评估长期暴露于大豆异黄酮的潜在不良影响（乳头吸出物中增生上皮细胞、闭经和低骨密度）。方法：200名女性（30 - 40岁，未服用避孕药，乳房x光检查正常）将被随机分配服用大豆异黄酮药丸（120毫克总苷元/天）（治疗）或安慰剂（麦芽糖糊精120毫克/天）（安慰剂），每周5天，持续2年。我们预测大豆饮食会降低乳房密度，可能还会降低骨密度，而这些乳房密度的降低与异黄酮的摄入有关。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Background: Populations consuming high levels of soy, as in many Asian countries, have lower levels of ovarian hormones, lower rates of breast cancer, and reduced mammographic density than populations consuming typical Western diets. These observations may in part be explained by our clinical studies that found ovarian hormone levels of premenopausal women to be lowest while they were consuming a diet that provided 15% energy from soymilk containing weakly estrogenic isoflavones. No adverse effects were observed. Further questions are whether isoflavones are the critical components influencing breast cancer risk and whether they do so by affecting other reversible risk markers for breast cancer, such as breast density. Aims: We propose to conduct a randomized, double-blind placebo controlled 2-arm study, with 200 premenopausal women (N=100/arm) to: (1) determine the effects of continuing exposure to isoflavones on serum levels of ovarian hormones and breast density and bone density and (2) assess potential adverse effects of chronic soy isoflavone exposure (hyperplastic epithelial cells in nipple aspirates, amenorrhea and low bone density). Methods: 200 women (30 to 40 years old, not on contraceptive, with normal mammograms) will be randomly allocated to take soy isoflavones in pills (120 mg of total aglycones/day) (treatment) or placebo (maltodextrin 120 mg/day) (placebo) 5 days per week for 2 years We predict that the soy diet will reduce breast density and possibly bone density, and that these reductions in breast density will correlate with isoflavone intakes.