Anastrozole: Drug that cuts breast cancer risk set for wider use in UK
Post-menopausal women in the UK who are at a higher risk of breast cancer may soon have wider access to a medicine called anastrozole to reduce their chance of developing it.
The drug, which is taken as tablets and was first developed as a treatment for breast cancer, halves the risk of the condition if taken for five years.
Anastrozole may already be used for prevention in those without breast cancer on an “off label” basis in many countries, including the US, but uptake is low. Now, the UK has become the first country where it has been approved for prevention.
This should encourage more family doctors to prescribe the drug, says Jack Cuzick at Queen Mary University of London, who was involved in a trial of anastrozole. “It will help doctors and women realise that it is an approved [use] and the benefits outweigh the risks.”
But anastrozole’s side effects – which are the same as severe menopausal symptoms, such as aching joints and hot flushes – can put people off taking it, says Liz O’Riordan, a UK breast cancer surgeon who has taken the drug herself. “It can be really hard.”
Women would be eligible to take anastrozole if they are at moderate or high risk of breast cancer, the Medicines and Healthcare products Regulatory Agency (MHRA) said on 6 November.
The agency hasn’t yet announced how this risk level would be defined, but it may include someone with at least one close relative, such as a mother or sister, who was diagnosed with the condition.
Anastrozole isn’t the only drug that can be used for breast cancer prevention. Another that is sometimes used is called tamoxifen, which can also cause menopause-like side effects, as well as raising the risk of blood clots.
Both drugs work by blocking the female sex hormone oestrogen, which promotes growth of breast cancer cells. Due to their different mechanisms, anastrozole can only be taken by women after they have gone through the menopause, while tamoxifen can be taken regardless of age.
Women can also reduce their risk of dying from breast cancer by having more frequent mammogram screenings and undergoing these scans at an earlier age. If women are at a high risk of breast cancer, for instance because they have inherited a mutation in a gene called BRCA1, they may choose to have their breasts surgically removed.
The addition of another option for women to lower their risk is welcome, says Dana Gheorghe at Citeline, a global pharmaceutical intelligence firm. “If people are willing to accept the side effects, it’s a nice modality.”