DAnIEL tagged this document as irrelevant
HRT breast cancer link claims spark row
Experts have attacked claims hormone replacement therapy causes breast cancer.
The link between HRT and the disease was made in a 2003 Cancer Research UK-funded report called the Million Women Study. It claimed the treatment doubles a woman’s breast cancer risk, while an update last August found “a rapid fall in risk after HRT is stopped”.
But experts writing in the Journal of Family Planning and Reproductive Health Care insisted the Million Women Study did not prove there was a connection.
The authors, from the UK, Germany and South Africa, said: “HRT may or may not increase the risk of breast cancer but the Million Women Study did not establish that it does.”
They say their analysis uncovered flaws in the design of the Million Women Study that would have skewed the findings.
For example, cancers detected within a few months of the study’s start would have already been present when the women were enrolled in the research - but these were not excluded, they said.
In the third report from the Million Women Study, follow-up data on HRT use was not available for 57% to 62% of the study participants. The researchers added: “The name ‘Million Women Study’ implies an authority beyond criticism or refutation.
“Many commentators, and the investigators, have repeatedly stressed that it was the largest study of HRT and breast cancer ever conducted.
“Yet the validity of any study is dependent on the quality of its design, execution, analysis and interpretation. Size alone does not guarantee that the findings are reliable.
“If the evidence was unreliable, the only effect of its massive size would have been to confer spurious statistical authority to doubtful findings.”
Hazel Nunn, head of health information at Cancer Research UK, said: “Women shouldn’t be unduly worried by this latest review of HRT and breast cancer risk.
“HRT can be an effective short-term treatment for menopausal symptoms - women taking it should try and use the lowest dose possible for as short a time as they need it.
“If you are considering starting or stopping HRT, or using it for a long time, you should discuss it with your doctor.”
She added: “In the UK, HRT use has been falling since the start of the millennium. Studies suggest that in 2005 there were 1,400 fewer cases of breast cancer in the UK among women aged 50 to 59 than would have been if there had been no drop in HRT use.”
Professor Dame Valerie Beral, lead author on the Million Women Study, said the issues raised by the latest research "are not new and have been refuted previously".
"The authors omit to say that Million Women Study findings of an increased risk of breast cancer in users of HRT, especially of oestrogen-progestogen combinations, have been replicated in over 20 other studies. The totality of the worldwide evidence is now overwhelming.
"In line with the findings from these studies, the recent large decrease in HRT use has been followed in many countries by a nationwide decline in the incidence of breast cancer."