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Monday 2 June 2008

RAPID ROUNDUP: Fall in HRT use Linked to Breast Cancer in Aussie Women (Medical Journal of Australia) – experts react.

A rapid fall in the use of hormone replacement therapy (HRT) in Australia has been linked to a recent reduction in invasive breast cancer among women aged 50 years or older, in the latest issue of Medical Journal of Australia. The study found that the use of HRT in Australia dropped, by 40 per cent from 2001 to 2003 and that during the same period, there was a significant 6.7 per cent drop in breast cancer rates among women aged 50 and over, which is equivalent to 600 fewer cases of breast cancer among Australian women.

The AusSMC has rounded up Australian experts to comment on this research. Feel free to use the comments below in your stories. If you would like to speak to an expert, or need a copy of the paper and press release, please don’t hesitate to contact us on (08) 8207 7415 or by email.

Professor Neville Hacker is Director of the Gynaecological Cancer Centre at the Royal Hospital for Women, Sydney.

“I am surprised by the magnitude in the reduction in breast cancer, but it does confirm previous studies that there is a link between use of HRT and increased incidence of breast cancer. I think the message from the study really is that risk of breast cancer from HRT is cumulative and that women should not take HRT for any longer than is necessary to control the symptoms of menopause.”

Professor Henry Burger is Former Director of Prince Henry’s Institute and an Honorary Professorial Fellow at Monash University. He is former president of the International Menopause Society.

“The authors from the NSW Cancer Council report a drop in hormone therapy use between 2001 and 2003 and an associated drop in the incidence of breast cancer over the same period. There is also a fall in breast cancer rates between 1998 and 1999 which appears to be of the same sort of magnitude and yet between 1998 and 1999 HRT prescription rates were actually increasing. The overall significance of the association is not impressive.

Rather surprisingly and puzzlingly their data shows a drop in HRT prescriptions from 2001 to 2002 – a year before the American Women’s Health Initiative report even linked HRT to breast cancer. It is not all clear why HRT prescriptions dropped between 2001 and 2002 but despite this there does not appear to be any change in breast cancer rates between during this period. There is only a very small albeit statistically significant change between 2002 and 2003 which is associated with a further fall in prescription rates.

If hormone therapy was a cause of breast cancer you would actually expect cancer rates to continue to increase even after a drop in prescription rates. For example breast cancer rates in the American Women’s Health Initiative study did not decline when woman stopped HRT at the end of the study. A decrease in breast cancer rates has also not been seen in the UK despite a drop in HRT prescriptions.

The investigators from the American Women’s Health Initiative have recently revised their conclusions from 2002 and have found that for women aged 50-59 (the group commonly prescribed hormone therapy) there is no significant increase risk in any adverse outcome and that the benefits outweigh the risks.

The International Menopause Society also recently published a report showing that hormone therapy in women 50-59 in a safe and effective treatment of menopause symptoms and is not associated with an increased risk of breast cancer. HRT is also probably the most effective therapy in preventing osteoporosis related fractures in this age group. This study does not in any way alter these conclusions.

My advice to women taking HRT for symptoms is that this report should not in any way change what they are doing. Women under the care of a practitioner should review their reasons for being on therapy every year as a matter of course. Women around the age of 50 who are contemplating HRT for moderate to severe menopause symptoms should be strongly reassured that it is a safe and effective therapy and that in the first 5 years there is no increase in breast cancer risk.”

Professor Anne Kavanagh is Director of the Key Centre for Women's Health in Society at the University of Melbourne.

“This study suggests that the decrease in the use hormone replacement therapy in Australian women over the age of 50 years is associated with the reduction in breast cancer incidence and is consistent with international evidence. HRT use, particularly combined use of oestrogen and progesterone therapies, is associated with an increase in breast cancer incidence and once women stop taking HRT this risk drops down to the average risk in the population.

A randomised control trial, released by the Women’s Health Initiative in 2002, showed that HRT use was linked with increases in the risks for breast cancer, coronary heart disease, thrombosis and stroke among women using HRT. Heavy media coverage of this trial was soon followed by a significant drop in HRT use worldwide. The decreased rates of observed breast cancer observed in Australia since that time are consistent with the drop in HRT use by Australian women.

Australia needs to develop a comprehensive database of prescription drug use, including HRT use, and to collect more information on the types of breast cancers that are diagnosed. Hormone therapy use is associated, in particular, with an increase in the risk what we call of oestrogen receptor positive’ breast cancers, but this information is not routinely collected by cancer registries. The information on HRT use and breast cancer incidence and mortality could be linked and this data could then be used to aid our understanding of the impact of hormone therapy on breast cancer incidence and mortality in Australian women.”