• Open Access

Serum phytoestrogens and prostate cancer risk in a nested case-control study among Japanese men

Authors

  • Kotaro Ozasa,

    Corresponding author
    1. Departments of Epidemiology for Community Health and Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566
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  • Masahiro Nakao,

    1. Departments of Urology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566
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      Department of Urology, Meiji University of Oriental Medicine, Hiyoshi-cho, Funai-gun, Kyoto 629-0392.

  • Yoshiyuki Watanabe,

    1. Departments of Epidemiology for Community Health and Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566
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  • Kyohei Hayashi,

    1. Departments of Epidemiology for Community Health and Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566
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  • Tsuneharu Miki,

    1. Departments of Urology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566
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  • Kazuya Mikami,

    1. Departments of Urology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566
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  • Mitsuru Mori,

    1. Department of Public Health, Sapporo Medical University School of Medicine, S1 W17, Chuo-ku, Sapporo 060-8556
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  • Fumio Sakauchi,

    1. Department of Public Health, Sapporo Medical University School of Medicine, S1 W17, Chuo-ku, Sapporo 060-8556
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  • Masakazu Washio,

    1. Department of Public Health, Sapporo Medical University School of Medicine, S1 W17, Chuo-ku, Sapporo 060-8556
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  • Yoshinori Ito,

    1. Department of Public Health, Fujita Health University School of Health Sciences, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake 470-1192
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  • Koji Suzuki,

    1. Department of Public Health, Fujita Health University School of Health Sciences, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake 470-1192
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  • Kenji Wakai,

    1. Department of Preventive Medicine/Biostatistics and Medical Decision Making, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550
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      Department of Urology, Meiji University of Oriental Medicine, Hiyoshi-cho, Funai-gun, Kyoto 629-0392.

  • Akiko Tamakoshi

    1. Department of Preventive Medicine/Biostatistics and Medical Decision Making, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550
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    Division of Epidemiology and Prevention, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Chikusa-ku, Nagoya 464-8681.

E-mail: kozasa@basic.kpu-m.ac.jp

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°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. (Cancer Sci 2004; 95: 65–71)

Abbreviations:
JACC Study

Japan Collaborative Cohort Study

SHBG

sex hormone-binding globulin

BMI

body mass index

OR

odds ratio

CI

confidence interval

SD

standard deviation

CV

coefficients of variation

CMA

chlormadinone acetate

PSA

prostate specific antigen

Ancillary