Research papers: Breast CancerPlasma enterolactone and genistein and the risk of premenopausal breast cancerPiller, Reginaa; Chang-Claude, Jennyb; Linseisen, Jakoba bAuthor Information aUnit of Human Nutrition and Cancer Prevention, Technical University of Munich bGerman Cancer Research Center, Department of Clinical Epidemiology, Heidelberg, Germany Correspondence to Professor Dr Jakob Linseisen, German Cancer Research Center, Department of Clinical Epidemiology, Nutritional Epidemiology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany Tel: +0049 6221 422363; fax: +0049 6221 42203; e-mail: [email protected] Received 22 March 2005 Accepted 6 July 2005 European Journal of Cancer Prevention: June 2006 - Volume 15 - Issue 3 - p 225-232 doi: 10.1097/01.cej.0000197449.56862.75 Buy Metrics Abstract Background The scientific debate on the role of dietary phytoestrogens for prevention of breast cancer is still ongoing. We previously reported an inverse association between dietary phytoestrogen intake and premenopausal breast cancer risk and now examine the relationship with plasma phytoestrogen concentrations. Methods We measured enterolactone (mammalian lignan) and genistein (isoflavone) concentrations in plasma samples of 220 premenopausal cases and 237 age-matched controls from a population-based case–control study in Germany. Results Median plasma enterolactone concentrations in cases and controls were 6.3 and 9.7 nmol/l, respectively, and median genistein concentrations were 4.5 and 3.7 nmol/l, respectively. Premenopausal breast cancer risk decreased with increasing plasma enterolactone concentrations. Adjusted odds ratios (95% confidence intervals) were 0.42 (0.20–0.90) and 0.38 (0.17–0.85) (P for trend 0.007) for women in the third and fourth quartile of plasma enterolactone compared to those in the lowest quartile. There was no significant association between plasma genistein concentration and premenopausal breast cancer risk. Conclusion Using biomarkers of phytoestrogen intake, we confirmed the strong inverse association between enterolactone and premenopausal breast cancer risk as found with dietary intake estimates. This result gives support to the potential role of mammalian lignans for breast cancer prevention among premenopausal women in Western populations. © 2006 Lippincott Williams & Wilkins, Inc.