Putting the risk of breast cancer and postmenopausal Hormone Therapy (HT) into perspective

Two similar comprehensive literature reviews and an editorial about the varying risk with different postmenopausal hormone therapy regimens have been published this month in Human Reproduction Update.

The reviews do not present new evidence but rather put together the main published studies and trials on this topic. Compared to the scare headlines that followed and sometimes misinterpreted the data in some studies, the overviews of all the results to date are partly reassuring and put the actual risk in perspective.

• For the third of postmenopausal HT-users who take oestrogen-only HT and do not have a uterus the best quality trial eg The Women’s Health Initiative (WHI) shows no increase in breast cancer rates after 7 years of therapy.
• For the many women who have a uterus and thus have to include a progestogen hormone with oestrogen therapy, to minimise uterine bleeding and uterine cancer, a significant increased risk was seen in the WHI Study ONLY after 5 years of combined oestrogen and progestogen therapy. Thereafter, there was an increase in breast cancer risk of approximately 4/10,000 per annum i.e. 1 for every 2,500 women per year.

The reviews by Professor John Collins’ team from Halifax, Canada and Dr Cladia Greiser’s team from Berlin, Germany could not determine whether the type, dose or route of the progestogen therapy changed the risk of breast cancer.

In an accompanying editorial by Professors Robert Norman and Alastair MacLennan of Australia, it was explained that the general risks and benefits of hormone therapy will vary greatly from woman to woman and the risks can often be minimised by selection of the most appropriate therapy at the appropriate time.

Professor MacLennan said “Up to 50% of women will benefit from the control of moderate to severe menopausal symptoms around menopause and for younger post-menopausal women, at risk of osteoporotic fractures, it is an effective option.” Furthermore, up to 20% of women in their 60’s and 10% in their 70’s may still require HT to alleviate symptoms.

As indicated not only by recent HT trials, but also supported by strong scientific evidence (fully described in a paper in Science June 2005 Mendelsohn et al) there appears to be a benefit in terms of heart and brain (memory) protection if HT is commenced around the time of menopause rather than many years after menopause. Further randomised clinical trials are required to test this hypothesis.

If long-term HT is used it is essential women are counselled not only about the breast cancer risk of their particular regimen but also the risks and benefits to all parts of their body. This is always an individual equation and an individual informed choice. These new reviews should help in decision-making.