Thousands of women offered anastrozole to help prevent breast cancer

The breast cancer treatment anastrozole has today been licensed as an option for preventing the disease in high-risk women in the UK. 

An estimated 289,000 post-menopausal women, most with a significant family history of breast cancer, could now be eligible to use anastrozole as a preventive treatment. A trial we funded showed that it can halve their risk.

Overall, research suggests that just one in four eligible women taking anastrozole should prevent around 2,000 cases of breast cancer. 

“Approaches to help prevent breast cancer in women at high risk are badly needed, so this is a welcome announcement,” said Dr David Crosby, head of prevention and early detection at Cancer Research UK. 

“We carried out some of the key work on developing these kinds of drugs, known as ‘aromatase inhibitors’, and ten years ago our clinical trial showed that anastrozole could halve the risk of some women developing breast cancer, with minimal side effects.” 

Previously, anastrozole was only licensed by the the Medicines and Healthcare products Regulatory Agency (MHRA) for use as a breast cancer treatment, which meant it was difficult to get it to women who could benefit from it as a risk-reducing option. It’s the first medicine the MHRA has relicensed as part of NHS England’s Medicines Repurposing Programme. 

One of the high-risk women who was offered anastrozole ‘off-label’ as a preventive drug is Lesley-Ann Woodhams. The 61-year-old completed the full five-year course of one tablet a day in January 2023. 

She said: “Taking anastrozole was an easy decision for me, as I’d watched my mum battle breast cancer and my risk was very high.  

“It really was a gift, it gave my family and myself peace of mind and more importantly, a continued future to look forward to. I’m grateful for every day I took this drug – it was life-changing. Anastrozole has allowed me to continue living my life as I’d planned.”

Because anastrozole is an older drug, it’s now off-patent, which means more than one company can produce it and it’s available more cheaply. The entire five-year course of treatment now costs just £78, or around 4p a day. Preventing 2,000 cases of breast cancer should also save £15m in treatment costs, according to NHS England. 

“Repurposing therapeutic drugs that have already been shown to be safe for prevention is an area with a lot of potential,” said Crosby. “More research will be key to finding more opportunities like this, to better understand who is at a high risk of getting cancer, and to help lower that risk.”  

He added: “If you have a family history of breast cancer and are worried about your cancer risk, speak to your doctor.”