Tens of thousands of women set to benefit from repurposed drug to prevent breast cancer

Clinical trials led by researchers at Queen Mary University of London have led to approval for anastrozole as a breast-cancer preventative drug.

The International Breast Cancer Intervention Study II (IBIS-II) recruited more than 3,800 postmenopausal women who were at increased risk of developing breast cancer. The participants received either anastrozole or a matching placebo daily for five years, and were followed up annually afterwards to check whether they had been diagnosed with breast or other cancers, or other health issues.

This study was led by Jack Cuzick, John Snow Professor of Epidemiology and Head of the Cancer Prevention unit in the Wolfson Institute of Population Health at Queen Mary University of London.

The study found that women receiving anastrozole were almost 50% less likely to be diagnosed with breast cancer, including invasive estrogen receptor-positive breast cancer and ductal carcinoma in situ. In 2017, the National Institute for Health and Care Excellence recommended anastrozole as a preventive option, however, with the treatment being unlicensed in this use, uptake has remained low.

The NHS Medicines and Healthcare products Regulatory Agency (MHRA) on 7 November licensed the use of this drug as a preventive option for women at increased risk, either due to genetic reasons or because of a significant family history of the disease. This new approval means that tens of thousands of post-menopausal women in the U.K. will now be able to receive treatment that will greatly reduce their risk of breast cancer.

NHS chief executive, Amanda Pritchard, said, "It's fantastic that this vital risk-reducing option could now help thousands of women and their families avoid the distress of a breast cancer diagnosis. Allowing more women to live healthier lives, free of breast cancer is truly remarkable, and we hope that licensing anastrozole for a new use today represents the first step to ensuring this risk-reducing option can be accessed by all who could benefit from it.

"This is the first drug to be repurposed through a world-leading new program to help us realize the full potential of existing medicines in new uses to save and improve more lives on the NHS. Thanks to this initiative, we hope that greater access to anastrozole could enable more women to take risk-reducing steps if they'd like to, helping them live without fear of breast cancer."

Professor Cuzick, who led the research, said, "Anastrozole is a very effective, safe and generally well-tolerated drug. It been shown to prevent about half the breast cancers in high risk postmenopausal women after an 11 year median follow up in the large international IBIS-II trial. The screening program provides an excellent opportunity to offer it to high risk postmenopausal women more routinely, and this would have a major effect on reducing the number of cases that occur."

Provided by Queen Mary, University of London