The true risks of HRT
John Stevenson (GB)
[Stevenson] Imperial College London
Many of the benefits of hormone replacement therapy (HRT) are well established, but have to be weighed against potential risks. The risks of HRT have frequently been overstated, either by reference to flawed observational studies or by flawed interpretation of existing data from randomised clinical trials. Increased breast cancer risk is a major concern, but there is little evidence that HRT causes breast cancer or increases its mortality. Indeed there is now evidence that certain estrogens may even reduce breast cancer risk. There is no convincing evidence that risk for ovarian cancer or any other cancer is increased by HRT. Risk for stroke is not increased when HRT is initiated early in the post-menopause and using appropriate doses and routes of administration; the risk for coronary heart disease is actually reduced. A transient increased risk for venous thrombo-embolism is seen with oral HRT and is dose dependent; it can be avoided by the use of non-oral therapy and perhaps by the use of very low oral doses at initiation of therapy. The increased risk for gallbladder disease may be confined to oral HRT use, and the absolute risk is extremely small. The fact that all-cause mortality is not increased by HRT, and indeed may be reduced, underlines the overall safety of the therapy even in the long term.