1. Endogenous Estrogens, Estrogen Metabolites, and Breast Cancer Risk in Postmenopausal Chinese Women.
- Author
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Moore, Steven C., Matthews, Charles E., Xiao Ou Shu, Kai Yu, Gail, Mitchell H., Xia Xu, Bu-Tian Ji, Wong-Ho Chow, Qiuyin Cai, Honglan Li, Gong Yang, Ruggieri, David, Boyd-Morin, Jennifer, Rothman, Nathaniel, Hoover, Robert N., Yu-Tang Gao, Wei Zheng, Ziegler, Regina G., Ou Shu, Xiao, and Yu, Kai
- Subjects
ESTRADIOL ,ESTRONE ,BREAST cancer risk factors ,POSTMENOPAUSE ,WOMEN'S health ,ASIANS ,BREAST tumors ,ESTROGEN ,METABOLISM ,RESEARCH funding ,STEROIDS ,DISEASE incidence ,CASE-control method ,ODDS ratio - Abstract
Background: The role of estrogen metabolism in determining breast cancer risk and differences in breast cancer rates between high-incidence and low-incidence nations is poorly understood.Methods: We measured urinary concentrations of estradiol and estrone (parent estrogens) and 13 estrogen metabolites formed by irreversible hydroxylation at the C-2, C-4, or C-16 positions of the steroid ring in a nested case-control study of 399 postmenopausal invasive breast cancer case participants and 399 matched control participants from the population-based Shanghai Women's Health Study cohort. Odds ratios (ORs) and 95% confidence intervals (CIs) of breast cancer by quartiles of metabolic pathway groups, pathway ratios, and individual estrogens/estrogen metabolites were estimated by multivariable conditional logistic regression. Urinary estrogen/estrogen metabolite measures were compared with those of postmenopausal non-hormone-using Asian Americans, a population with three-fold higher breast cancer incidence rates. All statistical tests were two-sided.Results: Urinary concentrations of parent estrogens were strongly associated with breast cancer risk (ORQ4vsQ1 = 1.94, 95% CI = 1.21 to 3.12, Ptrend = .01). Of the pathway ratios, the 2-pathway:total estrogens/estrogen metabolites and 2-pathway:parent estrogens were inversely associated with risk (ORQ4vsQ1 = 0.57, 95% CI = 0.35 to 0.91, Ptrend = .03, and ORQ4vsQ1 = 0.61, 95% CI = 0.37 to 0.99, Ptrend = .04, respectively). After adjusting for parent estrogens, these associations remained clearly inverse but lost statistical significance (ORQ4vsQ1 = 0.65, 95% CI = 0.39 to 1.06, Ptrend = .12 and ORQ4vsQ1 = 0.76, 95% CI = 0.44 to 1.32, Ptrend = .28). The urinary concentration of all estrogens/estrogen metabolites combined in Asian American women was triple that in Shanghai women.Conclusions: Lower urinary parent estrogen concentrations and more extensive 2-hydroxylation were each associated with reduced postmenopausal breast cancer risk in a low-risk nation. Markedly higher total estrogen/estrogen metabolite concentrations in postmenopausal United States women (Asian Americans) than in Shanghai women may partly explain higher breast cancer rates in the United States. [ABSTRACT FROM AUTHOR]- Published
- 2016
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