Leading article: The balance has changed

Hormone Replacement Therapy was once hailed as the answer for women who had reached the age of menopause and those experiencing the menopause ahead of time. It negated or moderated most of the unpleasant symptoms; it gave women of a certain age a new lease of life. For a generation of women who had been liberated by the contraceptive pill, it held the promise of another liberation almost as great.

More recently, the reputation of HRT as the miracle treatment has taken a few knocks, which was probably only to be expected. The notion that there could be a magic pill that mitigated the worst effects of the menopause without causing any adverse side-effects was always likely to be too good to be true.

But although the negative evidence was mounting quite consistently, the grounds for successive scares were often called into question. In the most widely circulated case, a US trial that was halted in 2002 after detecting a link between heart disease and HRT, another group of scientists subsequently described the methodology as flawed.

Now, just as HRT was starting to return to popularity, come the latest conclusions of the Million Women Study in Britain. They do not make cheerful reading. In several respects they confirm the worst fears raised by previous studies - and add to them. According to these findings, HRT may have caused as many as many as 1,000 deaths from ovarian cancer between 1991 and 2005. The same study shows that rates of breast cancer and endometrial cancer are also markedly increased. Overall, women taking HRT are 63 per cent more likely to contract one of these three common cancers than women who do not. There is also an increased risk of stroke and thrombosis.

The Million Women Study - the name of the project means what exactly what it says - is an ongoing project that involves a vastly greater number than any trial group. A thoroughly admirable endeavour, it is funded largely by Cancer Research UK - not by pharmaceutical companies that might have a commercial interest in the results.

It is hard not to conclude that the latest figures completely alter the balance of advantage from HRT. The total of one million women who are still taking HRT in this country - half as many as before 2002 - is now likely to fall again sharply.

Hormones, it is perhaps worth observing, are problematical in pretty much any form and at pretty much any age. The latest findings of the Million Women Study show that where hormone treatment is not medically necessary to sustain normal health, it is probably best left well alone.