Hormone replacement therapy use dramatically increases breast oestrogen receptor expression in obese postmenopausal women

BACKGROUND: It is known that use of hormone replacement therapy (HRT) by postmenopausal women increases the risk of breast cancer. METHOD: In this study, oestrogen receptor (ER)-α expression is examined using standard immunoperoxidase technique. RESULTS: Normal breast samples of 11 Australian postmenopausal women have been included in the ER-α study; the result showed a strong correlation (r(2) = 0.80) between ER-α expression in normal breast epithelial cells and body mass index (BMI) in normal women who currently use HRT. CONCLUSION: This finding confirms that the possibility of increased risk of breast cancer associated with increased ER-α expression in normal breast epithelial cells, in turn associated with high BMI and the use of HRT.