Researchers say they are getting closer to winning the war against breast cancer after a drug tested on Australian women was found to prevent the disease in those at high risk.
The much-anticipated results from the International Breast Cancer Intervention Study, or IBIS-II, show the drug anastrozole helped prevent breast cancer in women with a family history and had few side effects.
Preliminary results released at the San Antonio Breast Cancer Symposium in the US yesterday and published in The Lancet also suggested an unexpected benefit, with the drug lowering the incidence of other cancers.
Experts say the findings could help them understand how and why cells turn cancerous.
The study was launched by the Australian and New Zealand Breast Cancer Trials Group in 2006 and is considered landmark because it is about preventing rather than just treating breast cancer.
More than 3800 postmenopausal women with a family history of breast cancer joined the pioneering trial.
Half the women were given anastrozole, also known as Arimidex, and the remainder were given a placebo. On average they were aged 59 and 47 per cent of them had used hormone replacement therapy before the trial.
The researchers found that anastrozole was useful in preventing invasive and ductal carcinoma in situ breast cancers.
One of the chief investigators, Professor Christobel Saunders from the University of WA's school of surgery, said the study had the potential to benefit future generations of women.
"The findings from this research may provide a new approach to prevent breast cancer, not only for women today, but also for their daughters and granddaughters in the future," she said.
Cancer Council professor of clinical research Michael Millward, who helped recruit women to the study, said the findings were very promising for women at higher risk of breast cancer.
"It gives an option for them to reduce their risk and it's very gratifying that WA women gave their time and efforts to be part of this important trial," he said.
He said the finding about other cancers was encouraging.