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.
