ALL women at high risk of breast cancer should be given drugs commonly used to treat osteoporosis, a new report says.

The Cancer Institute NSW says 9000 Australian women could avoid developing breast cancer in the next five years if they took the drugs tamoxifen and raloxifene.

The institute's chief executive, Jim Bishop, said international trials had shown that these so-called selective oestrogen receptor modulators could reduce the risk of hormone-sensitive invasive breast cancer in about 70 per cent of high-risk women.

A woman is considered at high risk of breast cancer if her mother or sister has had the disease, or if two or more relatives were diagnosed before the age of 50.

"The opportunity to avoid breast cancer in around 70 per cent of high-risk, post-menopausal women is very encouraging, so there's a strong case for [the modulators] to now be used in Australia," Professor Bishop said.

While tamoxifen is used in Australia to treat osteoporosis and established breast cancer and raloxifene is used to treat osteoporosis, neither drug is used to prevent breast cancer.

The NSW Assistant Health Minister (Cancer), Verity Firth, welcomed the report and said she was keen to get the idea, which would cost $240 million a year, discussed widely.
 

"NSW will be providing this interesting research from the Cancer Institute to the appropriate federal health authorities," she said.

Evidence shows a five-year course of tablets may protect against breast cancer during that time and possibly for a further five years.

The drugs work by blocking oestrogen receptors in breast cells, preventing more powerful oestrogen signals from telling the cell to grow and spread as cancer.

The report also found use of the drugs would be cost-effective. The estimated cost of $240 million a year - or between $20,000 and $40,000 for every healthy life-year saved - is a worthwhile investment, Professor Bishop said.