title: Serum phytoestrogens and prostate cancer risk in a nested case-control study among Japanese men.
abstract: The purpose of this study was to examine whether a high serum concentration of phytoestrogens reduces the risk of prostate cancer in a case-control study nested in a community-based cohort in Japan (Japan Collaborative Cohort (JACC) Study). Information on lifestyles and sera of the subjects were collected in 1988-90, and they were followed up to 1999. Incident and dead cases of prostate cancer and controls were matched for study area and age. Phytoestrogens and sex hormones in sera stored at - 80 degrees C were measured in 2002. Of 14,105 male subjects of the cohort who donated their sera, 52 cases and 151 controls were identified. Three datasets were analyzed; 1) all subjects, 2) 40 cases and 101 controls after excluding subjects with low testosterone levels who were suspected of having had medical intervention, and 3) 28 cases and 69 controls with prostate specific antigen level of </= 10.0 ng/ml. The odds ratio (OR) for the highest level to the lowest was 0.38 (95% confidence interval (CI); 0.13, 1.13) for genistein, 0.41 (0.15, 1.11) for daidzein, and 0.34 (0.11, 1.10) for equol for the second dataset. Genistein and daidzein showed similar findings in the third one. Equol and equol/daidzein ratio showed consistent findings in all three datasets (OR = 0.39, 95% CI; 0.13, 0.89, trend P = 0.02 for the first dataset). Their effects seemed to be independent of serum sex hormones. In conclusion, serum genistein, daidzein, and equol seemed to dose-dependently reduce prostate cancer risk.
authors.affiliation: Department of Epidemiology for Community Health and Medicine, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kamigyo-ku, Kyoto 602-8566, Japan. kozasa@basic.kpu-m.ac.jp
authors.forename: Kotaro
authors.initials: K
authors.lastname: Ozasa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nakao
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Kyohei
authors.initials: K
authors.lastname: Hayashi
authors.forename: Tsuneharu
authors.initials: T
authors.lastname: Miki
authors.forename: Kazuya
authors.initials: K
authors.lastname: Mikami
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Mori
authors.forename: Fumio
authors.initials: F
authors.lastname: Sakauchi
authors.forename: Masakazu
authors.initials: M
authors.lastname: Washio
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Ito
authors.forename: Koji
authors.initials: K
authors.lastname: Suzuki
authors.forename: Kenji
authors.initials: K
authors.lastname: Wakai
authors.forename: Akiko
authors.initials: A
authors.lastname: Tamakoshi
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000097:blood; D016022:Case-Control Studies; D006801:Humans; D007529:Isoflavones / Q000097:blood*; D007564:Japan; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D048789:Phytoestrogens; D028321:Plant Preparations / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood*; D012307:Risk Factors
chemical_list: D014408:Biomarkers, Tumor; D007529:Isoflavones; D048789:Phytoestrogens; D028321:Plant Preparations