title: Serum estrogen receptor bioactivity and breast cancer risk among postmenopausal women.
abstract: The estrogen levels of Asian women are different from those of Western women, and this could affect estrogen receptor (ER) bioactivity and breast cancer risk. We conducted a case-control study in 169 postmenopausal breast cancer cases and 426 matched controls nested within a population-based prospective cohort study, the Singapore Chinese Health Study, to evaluate the serum levels of estrogens and their receptor (ERα and ERβ)-mediated estrogenic activities in relation to breast cancer risk. Breast cancer cases had higher levels of estrogens and ER-mediated bioactivities in baseline serum than the controls. Compared with those in the lowest quartile, women in the highest quartile for estrone (E1) or ERα-mediated bioactivity had increased breast cancer risk. After additional adjustment for ERβ bioactivity, free estradiol, and E1 levels, serum ERα-mediated bioactivity remained associated with increased breast cancer risk. Compared with those in the lowest quartile, women in the highest quartile for ERα-mediated bioactivity had an odds ratio of 2.39 (95% CI=1.17-4.88; P for trend=0.016). Conversely, the positive association between E1 and cancer risk became null after adjustment for ERα-mediated bioactivity, suggesting that the effect of E1 could be mediated through ERα. Factor(s) contributing to increased ERα-mediated estrogenic bioactivity in serum and its role as a predictor for breast cancer risk need to be validated in future studies.
authors: Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, NUHS Tower Block, Level 12, 1E Kent Ridge Road, Singapore 119228, Singapore National Registry of Diseases Office, Ministry of Health, Singapore 168937, Singapore Division of Cancer Control and Population Sciences, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15232, USA Department of Epidemiology, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania 15232, USA Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore 169857, Singapore Saw Swee Hock School of Public Health, National University of Singapore, Singapore 117597, Singapore.
authors: Vanessa W
authors: VW
authors: Lim
authors: Jun
authors: J
authors: Li
authors: Yinhan
authors: Y
authors: Gong
authors: Aizhen
authors: A
authors: Jin
authors: Jian-Min
authors: JM
authors: Yuan
authors: Eu Leong
authors: EL
authors: Yong
authors: Woon-Puay
authors: WP
authors: Koh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000097:blood* / Q000378:metabolism; D016022:Case-Control Studies; D004958:Estradiol / Q000097:blood; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D047629:Estrogen Receptor beta / Q000378:metabolism; D004970:Estrone / Q000097:blood; D005260:Female; D006367:HeLa Cells; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood*; D012306:Risk; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D012846:Singapore / Q000453:epidemiology
chemical_list: C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D012738:Sex Hormone-Binding Globulin; D004970:Estrone; D004958:Estradiol
keywords: breast cancer; estrogen; estrogen receptor; estrogen receptor bioassay