Can drugs prevent breast cancer?
A drug used as a breast cancer treatment has recently been authorized in the UK to be used for the prevention of breast cancer.
Research shows this drug, anastrozole can reduce the risk of breast cancer by 49% after 5 years of treatment in a specific group of women – postmenopausal women who are at high risk of breast cancer – who were followed-up over an average of 10 years.
How does anastrozole work?
Anastrazole is type of drug called an aromatase inhibitor. It works by reducing the production of oestrogen in fatty tissue. Before menopause, most oestrogen is made in the ovaries but this decreases significantly after menopause (post-menopause). In post-menopausal women, oestrogen is mainly produced in fatty tissue. Oestrogen drives some breast cancers. Aromatase inhibitors are therefore used in the treatment of breast cancer in post-menopausal women.
Are there side effects of anastrozole?
The use of anastrozole is however not without side effects. Because it reduces oestrogen levels, it can worsen menopause symptoms such as hot flushes and night sweats, sleep disturbance, vaginal dryness, joint pain and stiffness, and can also cause thinning of bones (osteoporosis). The medication is already used off-label in the US to prevent breast cancer in some women, but given the side effects, it is not suitable for everyone and may not be widely recommended for cancer prevention at this point.
What is needed is further research to tell us how to measure the pros and cons in order to allow women to decide if the drug is suitable for them. Standardized Risk Assessments – which use a woman’s personal data and family history – to accurately determine a woman’s individual risk of breast cancer is an important area of research. This will help women weigh their risk of breast cancer against the risk of preventive treatment and allow for informed decision-making guided by their doctors. Indeed this represents personalized medicine for cancer prevention, an exciting new frontier that’s not far on our horizon.
If you have any questions please do ask one of the Osler Health doctors.