Updated 24/03/15 in the light of Angelina Jolie Pitt’s announcement she has decided to have her ovaries removed as well – see below.
The news today is full of reaction to US actress Angelina Jolie’s decision to have surgery to reduce her chances of breast cancer.
She made this difficult decision because, having lost her mother to ovarian cancer, she discovered she carries a faulty copy of the BRCA1 gene – which put her at very high risk of getting both forms of the disease.
If you haven’t read her brave and thoughtful piece in the New York Times, it’s worth doing so.
But in the light of the considerable interest, and the fact that many people will undoubtedly have questions, we wanted to pull together a few quick thoughts and facts on the topic of inherited breast cancer generally, and the BRCA1 gene specifically.
How can you ‘inherit’ breast cancer?
No two people are born the same and, as a result, we all have slightly different chances of developing diseases during our lifetimes. This is the result of natural variation in our genes.
On top of this natural variation, about 1 in 1,000 people inherit a damaged copy of a BRCA1 gene from one of their parents, and this means their chance of developing a breast cancer is far higher than average. Families that carry these gene faults usually have a long history of breast and/or ovarian cancer.
But only a small proportion – about one in 20 (5 per cent) – of the 50,000 women diagnosed with breast cancer every year carries an inherited gene fault like BRCA1. Most breast cancers arise from genetic damage that accumulates over a person’s lifetime (that’s why age is the biggest risk factor).
So when we say these genes cause an ‘increased risk’, what do we mean?
The average woman in the UK has a 12.5 per cent chance of developing breast cancer at some point in her life. In other words, if you follow the lives of a hundred average women, 12 or 13 will eventually develop breast cancer.
But a female BRCA1 carrier has between a 60 and 90 per cent chance of developing breast cancer – in other words, between 60 and 90 out of every hundred BRCA1 carriers go on to develop breast cancer. They also have an around 40 – 60 per cent chance of ovarian cancer.
The precise figure for an individual woman will vary according to several things, such as a her age, the number of affected family members, and the exact nature of the fault in the gene.
In Ms Jolie’s case, she was told she had an 87 per cent chance of breast cancer. The double mastectomy surgery that she decided to have has reduced her breast cancer risk to around 5 per cent – less than the risk of an average woman in the general population.
We’ve got extensive information about breast cancer genes on our website.
So how do faults in BRCA1 actually cause breast cancer?
Understanding the BRCA1 gene
The link between the BRCA1 gene and breast cancer was discovered in 1994 (our researchers played a pivotal role, which you can read about here).
Further research showed that – in most of us – it tells cells to make a protein that helps repair damage to DNA.
So people who inherit a faulty copy are less able to repair damage that accumulates in their DNA over time. And so they’re at higher risk of cancer.
Is surgery the only option?
Women should make the decision that’s right for them. Surgery is not the only option – women can opt to have intensive surveillance for the early signs of breast cancer, either with mammograms or MRI scans. These can pick up cancers when they’re small, localised, and easier to treat successfully.
There are many factors that affect a woman’s decision, for example how old she is, or whether she’s had (or is planning to have) children. We applaud Angelina Jolie’s brave decision to speak publicly about her experiences, but we also want women to know that they shouldn’t feel pressured to have surgery if they’re not sure this is the right choice based on their own circumstances.
As well as her announcement in May 2013 that she had opted for a preventive double mastectomy, in March 2015 Angelina went public with the news that she had also decided to have her ovaries and fallopian tubes removed to reduce her risk of developing ovarian cancer – the disease the killed her mother at the age of just 56. Her choice to be open about her increased risk of breast and ovarian cancer helps to draw attention to the difficult decisions faced by women who have a BRCA gene fault.
For these women, having their ovaries removed can significantly reduce their risk of developing ovarian cancer and has an added effect of helping to reduce the chances of getting breast cancer too. However, it is important to remember that only a relatively small proportion of breast and ovarian cancers are caused by one of these gene faults, so only a small number of women will be faced with this difficult choice.
This feature, Decisions on a Knife Edge, published by Mosaic Science is an excellent in-depth exploration of some of the issues that women in this situation face. (Updated KA 24/03/15)
I’m worried I have cancer in my family – what can I do?
Mutations in the BRCA genes cause particular patterns of cancer down the generations. According to the National Institute for Health and Care Excellence (NICE), you may have a higher than average risk of breast cancer if you have one of the following in your family:
- A mother or sister diagnosed with breast cancer before the age of 40
- Two close relatives from the same side of the family diagnosed with breast cancer – at least one must be a mother, sister or daughter
- Three close relatives diagnosed with breast cancer at any age
- A father or brother diagnosed with breast cancer at any age
- A mother or sister with breast cancer in both breasts – the first cancer diagnosed before the age of 50
- One close relative with ovarian cancer and one with breast cancer, diagnosed at any age – at least one must be a mother, sister or daughter
The affected relatives must come from the same side of your family (either your mother’s side or your father’s side) and they must be your blood relatives. A close relative means a parent, brother or sister, child, grandparent, aunt or uncle, nephew or niece.
Risks are also higher among people of Ashkenazi Jewish descent.
If this sounds like you, you should talk to your GP – the NHS has excellent genetic counselling services. We have more information about family history and other proven breast cancer risk factors on our patient information website.
What work is Cancer Research UK doing in this area?
Over the years, supported by the British public, our researchers have played a pivotal role in indentifying and understanding breast cancer genes. Their research helped pin down BRCA1 in 1994 , and they found its close cousin – BRCA2 – a year later. It’s because of work like this that hundreds of thousands of women, including Angelina Jolie, can take positive steps to reduce their risk of the disease.
We’ve also made strides in understanding exactly how these gene faults lead to cancer, and are helping develop drugs called PARP inhibitors, which can target cancers driven by these faults. The first of these, olaparib (Lynparza) has now been approved in Europe and we hope it will soon be available for NHS patients here in the UK. (Updated KA 24/03/15)
And we’ve started to unravel why some BRCA1 carriers are at higher risk than others, which could help women make the tricky decision as to whether to have surgery or surveillance.
As well as our work on faulty genes, we’re also working hard on understanding the natural variation that affects breast cancer risk in the rest of us (albeit to a lesser degree). Just a few months ago, our researchers pinpointed 49 regions of our genetic code that are involved in breast cancer risk. Our vision is that this information can be integrated into the NHS screening programme, targeting screening better across the UK’s population.
And that brings us to our final point. Angelina Jolie’s story demonstrates clearly how the fruits of scientific research can help people take positive steps to take the fight to cancer. We’re not helpless – even though some of us are dealt a ‘bad hand’, genetically speaking.
Research has also shown us how those of us at ‘average’ risk of cancer, can take action too – living a healthy lifestyle, knowing the symptoms of the disease, and seeing a GP if you notice anything unusual.
And if you have questions or concerns about the disease, you can contact our nurses – either via email, or on 0808 800 4040, 9am-5pm.