Adverse neoplastic and cardiovascular outcomes of HRT: the validity of the evidence.

The possibility that HRT may increase the risk of cancer, female cancers in particular, has been a general concern ever since HRT was first advocated in the mid-1950s. For cancer of the uterus that concern was vindicated when it was shown that unopposed estrogens greatly increase the risk. However, because HRT is undoubtedly effective in relieving menopausal symptoms, and because it was thought that HRT may reduce the risk of coronary heart disease, the use of estrogens in combination with progestins soon supplanted unopposed estrogen use (if less so among women who had undergone hysterectomies), in the belief, soon confirmed by epidemiological evidence, that combined therapy probably eliminates any increase in the risk of uterine cancer, or perhaps even reduces it.