1. ¹Cancer Epidemiology Unit, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7LF, UK
2. ²Department of Clinical Epidemiology, Aarhus University Hospital, Aalborg, Denmark
3. ³Institute of Cancer Epidemiology, Danish Cancer Society, Copenhagen, Denmark
4. ⁴Division of Cancer Epidemiology, German Cancer Research Centre, Heidelberg, Germany
5. ⁵German Institute of Human Nutrition, Potsdam-Rehbruecke, Nuthetal, Germany
6. ⁶National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
7. ⁷CPO-Piedmonte and ISI Foundation, Torino, Italy
8. ⁸Molecular and Nutritional Epidemiology Unit, CSPO-Scientific Institute of Tuscany, Florence, Italy
9. ⁹Cancer Registry Azienda Ospedaliera Civile-M.P. Arezzo, Ragusa, Italy
10. ¹⁰Department of Preventive and Predictive Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
11. ¹¹Department of Hygiene and Epidemiology, University of Athens Medical School, Athens, Greece
12. ¹²Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA
13. ¹³Hellenic Health Foundation, Athens, Greece
14. ¹⁴Epidemiology Department, Murcia Health Council, CIBER en Epidemiología y Salud, Pública (CIBERESP), Murcia, Spain
15. ¹⁵Public Health Institute of Navarra, Pamplona, Spain
16. ¹⁶CIBER Epidemiología y Salud Pública (CIBERESP), Spain
17. ¹⁷Public Health Department of Gipuzkoa, Basque Government, Donostia-San Sebastian, Spain
18. ¹⁸Unit of Nutrition, Environment and Cancer, Catalan Institute of Oncology, Barcelona, Spain
19. ¹⁹Public Health Directorate, Population Health Service, Health Information Section, Asturias, Spain
20. ²⁰Andalusian School of Public Health, Granada, Spain
21. ²¹Department of Public Health and Primary Care, MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival, University of Cambridge, Cambridge, UK
22. ²²Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK
23. ²³Department of Public Health and Clinical Medicine, Nutritional Research, Umeå University, Umeå, Sweden
24. ²⁴Department of Surgical and Perioperative Sciences, Urology and Andrology, Umeå University, Umeå, Sweden
25. ²⁵International Agency for Research on Cancer, The World Health Organisation, Lyon, France
26. ²⁶Department of Epidemiology and Public Health, Imperial College, London, UK

Correspondence: Dr RC Travis, E-mail: ruth.travis@ceu.ox.ac.uk

Received 28 January 2009; Accepted 9 April 2009; Published online 12 May 2009.

Abstract

We examined plasma concentrations of phyto-oestrogens in relation to risk for subsequent prostate cancer in a case–control study nested in the European Prospective Investigation into Cancer and Nutrition. Concentrations of isoflavones genistein, daidzein and equol, and that of lignans enterolactone and enterodiol, were measured in plasma samples for 950 prostate cancer cases and 1042 matched control participants. Relative risks (RRs) for prostate cancer in relation to plasma concentrations of these phyto-oestrogens were estimated by conditional logistic regression. Higher plasma concentrations of genistein were associated with lower risk of prostate cancer: RR among men in the highest vs the lowest fifth, 0.71 (95% confidence interval (CI) 0.53–0.96, P trend=0.03). After adjustment for potential confounders this RR was 0.74 (95% CI 0.54–1.00, P trend=0.05). No statistically significant associations were observed for circulating concentrations of daidzein, equol, enterolactone or enterodiol in relation to overall risk for prostate cancer. There was no evidence of heterogeneity in these results by age at blood collection or country of recruitment, nor by cancer stage or grade. These results suggest that higher concentrations of circulating genistein may reduce the risk of prostate cancer but do not support an association with plasma lignans.