Q&A: Drugs to prevent breast cancer
New guidelines for England, Wales and Scotland say women with a strong family history of breast cancer could take a course of tablets to cut their own risk of the disease.
This gives women a choice other than mastectomy or close monitoring.
But which option is best?
Why are doctors now recommending drugs?
The NICE guidelines for England and Wales, and separate guidelines in Scotland, say there is good evidence that drugs can help stop breast cancer if they are taken for five years.
Studies suggest that tamoxifen or another drug called raloxifene can halve a woman's risk of breast cancer if she takes a daily course for five years. And it's thought that benefit lasts for at least a decade after the course ends.
Are drugs the best option then?
That is unclear.
Some women may prefer to take drugs than have invasive treatment such as surgery to remove both breasts.
However, for others, having a mastectomy may be more appealing because it reduces the risk of breast cancer to almost zero.
Other women may not want any treatment since both surgery and drugs carry risks and side effects. Instead, they might opt for close monitoring so that any tumour will be detected early on.
How do I know if I am at risk of breast cancer?
Most breast cancers aren't inherited and occur by chance. Age is one of the biggest factors that affects breast cancer risk.
Women, in general, have a 1-in-8 chance of getting breast cancer at some stage of their life, with most of these cancers affecting women over the age of 50.
But about one in five women diagnosed with breast cancer has a significant family history of the disease - close family members such as a mother or sister who developed breast cancer at a young age, for example.
The new NICE guidelines apply to such women who have a 'moderate' or 'high' risk of developing breast cancer.
By this they mean women with at least a 1-in-6 chance of getting breast cancer.
If you think you may fit this category, you should see your doctor to discuss your breast cancer risk.
Your doctor will be able to take a detailed family history from you and may want to run some tests to check wither you have inherited certain genes linked with breast cancer.
How do I choose between surgery, drugs and monitoring?
It is important to talk to your doctor so that you have enough information to weigh up the risks and merits of each treatment option.
Tamoxifen is not suitable for every woman - if you are trying for a baby you should not take it, for example. And it can cause unpleasant and dangerous side effects, including hot flushes and blood clots.
NICE says women over 35 might consider drug treatment.
Although the treatment might work for women who are younger than this, the risk of side effects might outweigh any potential benefits. Cancer risk goes up with age, so women are unlikely to get breast cancer in their 20s and early 30s even if they have a strong family history of the disease.
While tamoxifen cuts breast cancer risk, some women on the drug will still go on to get breast cancer. And it's not clear whether preventive tamoxifen has any impact on breast cancer deaths.