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Editor, – A recent article by Professor S.K. Khoo (Aust Prescr 1993;16:66-8) discussed the safety of hormone replacement therapy (HRT) in postmenopausal women. Despite the plethora of information being published in the medical arena in support of this therapy, there remain real controversies about some aspects of its safety, especially with respect to breast cancer.

In women without prior cancer, a meta-analysis of 16 published studies demonstrated a relatively small (30%) but statistically significant increase in breast cancer risk.¹ Of even greater importance is the finding that in women with a family history of breast cancer using some form of HRT, this risk increased 3-fold (confidence limits 2-6)compared to those who had never used oestrogen replacement therapy. This issue was not adequately addressed by the author. It is important for women to be able to make an informed decision. However, such informed decision making is not possible unless the evidence presented to the medical profession is clear and unbiased.

Whilst HRT is clearly beneficial for the control of menopausal symptoms, the use of such therapy in women at a higher risk of developing breast cancer should be at least clearly presented and we believe, strongly discouraged until further data provide evidence for the safety of such therapy.

Dr John Zalcberg
Director, Medical Oncology
and
Mr Jim Siderov
Senior Oncology Pharmacist
Department of Medical Oncology
Heidelberg Repatriation Hospital
Heidelberg West, Vic.

Professor S.K. Khoo, the author of the article, comments:
I agree that there is still continuing concern about the risk of breast cancer in postmenopausal women using HRT.

The epidemiological data reviewed in the section on 'Risk of breast cancer' is brief because of space restrictions; a fuller review is given elsewhere.² Overall, the message from these data is reassuring in my view. In fact, if we accept that a large prospective study has a higher power of analysis, the Nurses Health Study³ involving120 000 women for 360 000 person-years of follow-up is revealing. It found that only current users who reported alcohol consumption had a significantly increased relative risk of breast cancer, 1.56 (95% confidence interval 1.2to 2.0); the risk in those users who reported no alcohol consumption was not increased, 0.99 (0.62 to 1.60). Undoubtedly, further studies are required to resolve the concern, but on the basis of present data, the established benefits of HRT would outweigh the risks especially in reducing cardiovascular and cerebrovascular deaths.