ANASTROZOLE MAINTAINS A PREVENTATIVE EFFECT

Long-term follow up results of the IBIS-II clinical trial shows that anastrozole maintains a preventative effect for postmenopausal women at high risk of breast cancer for at least 12 years.

The results, published in The Lancet and presented at the San Antonio Breast Cancer Symposium in the United States, shows that the drug offers significant long-term protection for women who take it for a total of five years. Seven years after trial participants last took the drug, invasive breast cancer and DCIS incidence was 49 per cent lower than in women given a placebo.

The international prevention clinical trial IBIS-II enrolled almost 4,000 women worldwide, with 818 women from Australia and New Zealand across 30 institutions. The trial was coordinated in Australia by Breast Cancer Trials (BCT) and globally by Cancer Research UK.

The first results of this study were previously reported in 2013 and found that taking anastrozole for five years reduced the chances of postmenopausal women at above average risk of developing breast cancer by 53% compared to women who took a placebo.

Dr Nicholas Zdenkowski is the BCT Study Chair of the IBIS-II clinical trial, following the retirement of Professor John Forbes AM, and says this latest analysis of the IBIS-II data confirms that anastrozole should be a valid choice for postmenopausal women with a family history of breast cancer or other risk factors.

“Anastrozole inhibits the production of oestrogen in postmenopausal women and has been used for a number of years now in the treatment of postmenopausal women with oestrogen receptor positive breast cancer,” Dr Zdenkowski said.

“We know that this class of drugs called aromatase inhibitors, is more effective than tamoxifen in women who have already had breast cancer. This latest report also confirms past research that anastrozole is a safe drug in the long-term.”

“This research provides women with greater options when it comes to managing their risk.”

These results show that the rate of breast cancer and DCIS can be cut in half in women who have a higher than average risk of breast cancer. This means that for every 29 women treated with anastrozole, one diagnosis of breast cancer or DCIS will be prevented. The protective effects continue for at least 7 years after stopping the drug.

Breast Cancer Trials – www.breastcancertrials.org.au – has been conducting clinical trials research for more than 40 years and the results have improved the treatment of the disease which has saved millions of lives through research collaboration. The research program brings together about 800 researchers in 102 institutions throughout Australia and New Zealand. More than 15,700 women have participated in BCT clinical trials.

Journal Reference:

Cuzick, J., et al. (2019) Use of anastrozole for breast cancer prevention (IBIS-II): long-term results of a randomised controlled trial. The Lancet. doi.org/10.1016/S0140-6736(19)32955-1.

Media contact: Anna Fitzgerald, BCT Communications Manager 0400 304 224 or anna.fitzgerald@bctrials.org.au. 

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