Pills to prevent breast cancer
A NEW way of tackling the scourge of breast cancer could be round the corner – with doctors prescribing a pill to prevent it in the first place.
At the moment the best way to avoid breast tumours is through a healthy lifestyle. But there are drugs that can stop some women from getting the disease and save thousands of lives.
These are not routinely used on the NHS because doctors have been unsure who would benefit the most and who would suffer nasty side-effects. Now a panel of experts has said that scientific trials should soon give them the answers to these questions.
Breast cancer is the most common cancer in women worldwide and more than 45,000 cases a year are diagnosed in the UK alone. Recent breakthroughs mean we now know more than ever about why some people get the disease, and the genes that cause tumours.
But in the general population around one in 10 women are at increased risk based simply on the density of their breasts. Writing in the journal Lancet Oncology today, scientists say they are close to understanding which of these women would benefit from drugs to prevent breast cancer as well as which drugs to use. Although it may be another decade before this type of approach – called preventative therapy - is widely used, it could fundamentally alter the way thousands of women are treated.
Being able to accurately predict breast cancer risk and who will respond to preventative drugs like these is a crucial step
Not only could they be identified during routine breast scans, but they could then be offered drugs, such as tamoxifen, to prevent them from getting the disease.
Professor Jack Cuzick, a Cancer Research UK epidemiologist based at Queen Mary, University of London who led the panel, said: “There’s strong evidence to show that drugs such as tamoxifen are effective at preventing breast cancer in women with greater than average risk of the disease.
“But it’s important to find ways of predicting who will respond, so drugs like this can be targeted at those most likely to benefit and least likely to experience side effects.
“Increased breast density is one of the leading risk factors for breast cancer and early trial results suggest that where tamoxifen is shown to decrease density the risk of cancer decreases.
“If this is confirmed in long-term studies, breast density could become a powerful way to identify high-risk women who could benefit from preventive treatments.”
Despite being a brilliant drug to treat breast cancer, tamoxifen has not proved popular as a drug to prevent the disease.
Large international trials have shown that although it reduces the risk of the most common kind of breast cancer - known as oestrogen receptor positive breast cancer - by around a third in women at increased risk, it has proved hard to know which women benefit the most.
Side-effects include hot flushes, blood clots and in some cases womb cancer which has prevented its widespread use.
But a current trial using tamoxifen should reveal which women do respond well when it is used to prevent breast cancer.
And even more importantly, a separate trial will reveal if other, newer drugs could be as effective in preventing cancer but without nasty side-effects.
The IBIS II trial will show if drugs called aromatase inhibitors can prevent cancer in certain women at high risk. Previous studies suggest it could reduce the risk of one type of breast tumour by a staggering 75 per cent.
However, the full results are not due for another five to ten years.
But if they prove positive, testing women’s breast density and offering preventative therapy could be as useful as testing cholesterol levels to decide which patients need to take statins to prevent heart attacks.
Dr Lesley Walker, Cancer Research UK’s director of cancer information, said: “Being able to accurately predict breast cancer risk and who will respond to preventative drugs like these is a crucial step in ensuring women get the most suitable treatment.”
Meg McArthur, Senior Policy Officer at Breakthrough Breast Cancer added:
“It is vital that we find effective ways to prevent breast cancer, especially in women with a high risk. However, as preventative therapy may have negative side effects it would not be appropriate for everyone.
“We welcome studies investigating the best treatments to be used for breast cancer prevention. It’s also crucial to identify those at high-risk who would benefit the most from this form of therapy.”
