04.18.08
Indication: Breast cancer
Source: J Clin Oncol, April 1, 2008;26(10):1677-83.
Research: Because they have large variations in consumption, Asian countries are suitable settings for studies of the effect of relatively high-dose isoflavone intake on breast cancer risk. Nevertheless, no prospective study from Asia has ever assessed blood or urine levels as biomarkers of isoflavone intake. For this study, researchers evaluated a total of 24,226 women, aged 40 to 69 years, who participated in the Japan Public Health Center-based prospective study. These subjects provided data through a baseline questionnaire and provided blood in 1990 and 1995. They were observed through December 2002.
Results: During a mean 10.6 years of follow-up, 144 patients newly diagnosed with breast cancer were identified. Two matched controls for each patient were selected from the cohort. Isoflavone levels were assessed by plasma level and food frequency questionnaire, and the odds ratio of breast cancer according to isoflavone level was estimated using a conditional logistic regression model. Researchers found a statistically significant inverse association between plasma genistein and risk of breast cancer, but no association for plasma daidzein.