EurekAlert! -- While endogenous estrogen (i.e., estrogen produced by ovaries and by other tissues) does have a well-known carcinogenic impact, hormone replacement therapy (HRT) utilizing estrogen alone (the exogenous estrogen) provides a protective effect in reducing breast cancer risk, according to study results presented at the 33rd Annual CTRC-AACR San Antonio Breast Cancer Symposium, held Dec. 8-12.
