HRT now linked to cancer of the womb

May 1 2005

A new study of more than 700,000 women has found, say the researchers, that Hormone replacement therapy (HRT) can increase the risk of cancer of the womb, depending on the form of HRT used.

Women taking oestrogen-only HRT, or a newer form of the therapy called Tibolone, are at an increased risk of the disease, compared with women who have never taken HRT. The risk is slightly reduced in women taking a combination of oestrogen and progesterone compared with those who have never taken HRT.

To confuse the issue even further researchers say that this does not mean that women should opt for the combined pill, because earlier research shows that this type of HRT poses a greater breast cancer risk than Tibolone or oestrogen-only HRT.

The fact that breast cancer is commoner than endometrial cancer means that statistically the balance is tipped in favour of the oestrogen-only or tibolone therapies and only further underlines that no form of HRT is without risk.

The study shows that about three out of every 100 women on combined HRT will develop either breast or endometrial cancer within five years compared to 2½ per 100 who take oestrogen- only HRT or tibolone, and about 1½ per 100 who do not take any form of HRT.

Valerie Beral, the director of the Cancer Research UK epidemiology unit, and lead author of the study, says the results will create a dilemma for women who want or need to use HRT.

The use of combined and oestrogen-only HRT has dropped during the past three years but the figures for the use of Tibolone have remained static and it is now the most common brand of HRT prescribed to women in the study.

John Toy, medical director of Cancer Research UK, advises that women should take HRT for medical need only and for the shortest time possible and says it is crucial that the effects that drugs can have on our bodies is clearly understood. Toy says that women, and the doctors who treat them, must be given all the information they need before making a decision to take HRT.

The study is published in the current edition of the Lancet.