The soy isoflavone daidzein improves the capacity of tamoxifen to prevent mammary tumours Andreas I. Constantinoua, , 1, , Bethany E.P. Whitea, 1, Debra Tonettib, Yanan Yangc, Wenzhong Liangc, Wenkui Lic and Richard B. van Breemenc aDepartment of Surgical Oncology, University of Illinois at Chicago, 840 South Wood Street, Chicago, IL 60612, USA bDepartment of Biopharmaceutical Sciences, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612, USA cDepartment of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 833 South Wood Street, Chicago, IL 60612, USA Abstract The aim of this study was to determine how the efficacy of tamoxifen is affected when combined with soy isoflavones. To address this, female Sprague–Dawley rats were placed on diets supplemented with tamoxifen, genistein, daidzein, or a combination of each isoflavone with tamoxifen; a week later mammary tumours were induced by 7,12 dimethylbenzanthracene. The most effective diet was the tamoxifen/daidzein combination. It reduced tumour multiplicity by 76%, tumour incidence by 35%, tumour burden by over 95%, and increased tumour latency by 62% compared with positive controls. The tamoxifen/daidzein combination diet was in all aspects more effective while the tamoxifen/genistein combination was less effective than the tamoxifen diet. The tamoxifen/daidzein diet significantly decreased 8-oxo-deoxyguanosine levels (an indicator of oxidative DNA damage) in the mammary glands. This study conclusively shows for the first time the combination of daidzein with tamoxifen produces increased protection against mammary carcinogenesis, while the combination of genistein with tamoxifen produces an opposing effect when compared with tamoxifen alone. doi:10.1016/j.ejca.2004.12.005 European Journal of Cancer Volume 41, Issue 4 , March 2005, Pages 647-654 Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.