New study says cancer risk from HRT only moderate
pharmafile | August 10, 2005 | News story | Research and Development |
The risk of developing breast cancer while on hormone replacement therapy may be lower than thought, according to a new study.
Researchers at the New South Wales Breast Cancer Institute in Australia used the latest data to estimate a woman's individual risk of breast cancer up to the age of 79 in relation to HRT – an approach known as cumulative absolute risk.
Previously, the only breast cancer risk data available had been for entire populations, which made the HRT risk seem greater than expected.
The latest study, published in the British Medical Journal, showed the average risk of a 50-year-old women developing breast cancer without HRT is 6.1%.
The risk increased to just 6.7% when she took combined HRT for five years and 7.7% for around 10 years.
"Although we found the additional breast cancer risk with hormone replacement therapy for an individual is very small, the effect on the general incidence of breast cancer would be greater, especially in populations with high levels of use," commented Professor John Boyages, the director of the institute.
The researchers pointed out in the study that once HRT was stopped, a woman's risk of breast cancer quickly returns to that of someone who has never used it.
The study results will be welcomed by HRT manufacturers, such as Wyeth, Novartis and Pfizer. Sales of HRT products have declined in recent years because of a welter of negative press linking them to risk of heart disease, dementia and cancer.
In 2002, the National Institutes of Health (NIH) said it was halting part of a study looking into combined HRT therapies because of health concerns linking treatments to risks of cancer and stroke.
Wyeth has subsequently launched low-dose versions of two HRT products, Premarin and Prempro, and its sales and marketing is now geared towards these new doses.
But sales of its Premarin family of HRT treatments fell sharply from around $1.25 billion in 2003 to $880 million in 2004, although Wyeth said the launch of its low doses had moderated the fall in sales.
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