Study assesses total and specific isoflavones, tumor characteristics, and menopausal status
TUESDAY, Nov. 9 (HealthDay News) -- Phytoestrogens found in soy may influence the risk of some types of breast cancer, according to research presented at the American Association for Cancer Research's Frontiers in Cancer Prevention Research Conference, held from Nov. 7 to 10 in Philadelphia.
Anne M. Weaver, of the Roswell Park Cancer Institute in Buffalo, N.Y., and colleagues analyzed data from 683 women with newly diagnosed breast cancer and 611 women without a history of the disease. The researchers calculated their intake of total and specific isoflavones from food-frequency questionnaires.
The researchers found that cases in the highest tertile of isoflavone intake had roughly 30 percent lower odds of an invasive tumor and 60 percent lower odds of a grade 1 tumor than those in the lowest tertile. In premenopausal women, greater intakes of total isoflavone, daidzein, genistein, and glycetein were associated with roughly 70 percent lower odds of a tumor greater than 2 cm in size. Premenopausal women in the highest tertile of total isoflavone and genistein intake (versus the lowest) had roughly 60 percent lower odds of stage II breast cancer.
"In this study, there is little evidence that isoflavones are associated with indicators associated with poor prognosis or recurrence, suggesting that these compounds may operate through mechanisms specific to the biologic heterogeneity of the tumor. Further research is warranted to address the impact of tumor heterogeneity in studies of isoflavones and breast cancer," the authors conclude.