Estrogen

HRT is absolutely contraindicated in women with undiagnosed vaginal bleeding, breast or endometrial cancer, and active deep vein thrombosis. Women with previous clotting disorders, especially in the setting of pregnancy, should be specifically evaluated medically before initiating HRT. Use of HRT after a diagnosis of melanoma remains controversial, and concerns have been raised regarding the use of HRT in women with liver disease or previous gallbladder disease. Other potentially important side effects that have not been adequately analyzed include immunological changes, in light of the presence of receptors for estrogen in various immune cells.

The most controversial aspect of HRT remains the potential increase in breast cancer resulting from long-term estrogen use. There are recognized experts on each side of the debate, but the majority of studies support no significant increase in breast cancer risk in women receiving postmenopausal HRT. Clearly, resolution of this important issue requires a randomized-controlled trial with longitudinal data. In any case, for women who have proven breast cancer or who have a known risk of developing breast cancer, postmenopausal HRT is contraindicated. The safety of HRT after breast cancer remains controversial, with available evidence neither assuring safety nor proving any toxic effects.