The largest ever study into the link between HRT and breast cancer was conducted by scientists at Cancer Research UK's Epidemiology Unit in Oxford.
The view of complementary practitioners has now been confirmed by Cancer Research UK's Epidemiology Unit. This study is in line with another by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health in the USA which, on July 9, 2002, announced that they would stop a major clinical study of the type of postmenopausal hormone therapy in which estrogen is combined with progestin. The study, a part of the Women's Health Initiative, found increases in breast cancer, cardiovascular disease, stroke, and blood clots in study participants who were taking estrogen plus progestin comparedwith women taking placebo pills.
The irony is that many of the natural products such as natural oestrogens, herbal supplements, or so-called plant estrogens (phytoestrogens) being used by complementary practitioners to help relieve women of menopausal symptoms are at risk of being banned or heavily restricted by EU Directives on food supplements and herbal medicines.
The research suggests the single pill moderately increases the risk of breast cancer, but the combined pill doubles the risk.
It estimates HRT may be responsible for an extra 20,000 cases of the disease in Britain.
The Committee on the Safety of Medicines has reviewed the data and written to all health professionals.
They stressed short-term HRT use is still beneficial, but those taking it for more than a year should heed the risks and discuss them with their GP.
If women are put on HRT, they should be screened for breast cancer every year as a matter of course
Barbara Sims took the combined HRT for six years before being diagnosed with breast cancer.
But she said she had no regrets because it rescued her from an early menopause and may have helped the detection of the cancer.
"Because my symptoms were so debilitating I couldn't lead a normal life at all," she said.
About 1.5million women in the UK take HRT, with half taking the combined version.
The researchers estimate there have been 20,000 cases of breast cancer over the last decade in women aged 50 to 64 because of HRT.
They say combined HRT is responsible for 15,000 of those cases.
The study is also the first to report that HRT increases the risk of dying from breast cancer, by 22%.
About 20 women in every 1,000 will usually develop breast cancer.
But the study found for every 1,000 women who use HRT for 10 years from the age of 50, there will be an additional 19 cases of cancer in those using the combined oestrogen and progestogen version and an extra five in those using oestrogen-only HRT.
It would be sensible for a woman to take HRT for only as long as it is necessary to deal with her medical problems
Dr John Toy Cancer Research UK
Using tibolone, a steroid treatment, also increased a woman's cancer risk.
Women also have to bear in mind that oestrogen-only HRT carries an increased risk of uterine cancer.
Women's risk of developing breast cancer decreases when she stops and is back to normal levels after five years, claims the research.
The data, published in The Lancet, covered a million women who went for mammograms between 1996 and 2001.
Professor Valerie Beral, who led the research, said: "Since our results show a substantially greater increase in breast cancer with combined HRT, women need to weigh the increased risk of breast cancer caused by the addition of progestogen against the lowered risk of uterine cancer."
Dr John Toy, Medical Director of Cancer Research UK, said: "It would be sensible for a woman to take HRT for only as long as it is necessary to deal with her medical problems as advised by her doctor.
"A woman wanting to take HRT for a long time would be extremely wise first to consider carefully the findings of this large study and other relevant research."