Would you take a test to find out your chance of inheriting breast cancer?
PUBLISHED: 15:38 15 October 2018
2015 Parpoulas Thomas Andreas
Breast cancer affects one in eight women – but would knowing if you were at risk of the disease help or hinder?
We can inherit a lot of things from our mothers, both good and bad. I know that I get my sense of humour, my love of reading and my fear of snakes from mine – but could I have inherited something more life-threatening?
My mum was diagnosed with breast cancer when I was seven – a life event that I barely remember now but which, at the time, was terrifying. In the decades since, she has gone for regular breast screenings, attended clinics, and been seen by a team of doctors who have, repeatedly, offered reassurance that everything is OK.
As a result, breast cancer – or the lingering threat of it – has been a part of my life for more years than not. And as our awareness of inherited diseases has increased, I’ve often wondered: could the threat extend even further – to me, to my sister, to my future children?
According to Cancer Research UK, between 5 to 10% of breast cancers are caused by an inherited faulty gene. “The risk of breast cancer in the general population is about 12% over a person’s lifetime (up to age 80),” says Dr Hannah Rawlins, breast physician at the Norfolk and Norwich University Hospital (NNUH). “But for ladies with a BRCA1 alteration it’s up to 90% and for BRCA2 it’s up to 85%.” So how can you know if you are a potential carrier?
Genetic testing is available for some people on the NHS. “But the process is very labour and time intensive,” says Dr Rawlins. “For this reason we select the patients who are most likely to be carriers. We work out those patients who have a more than 10% chance of being a gene carrier and these people are offered testing.”
There are two types of people who are offered the test, adds Dr Rawlins: “Firstly, those patients with cancer who fulfil certain criteria (for example, are under 30 at diagnosis or who have also had a certain type of ovarian cancer). Some other patients will also be offered testing if they have had breast cancer and there’s a significant family history of breast or ovarian cancer, suggestive of a possible abnormal gene.
“Secondly, unaffected patients with a close relative found to carry one of the genes will be offered testing. If a mother or father is a carrier there’s a 50% chance of passing the gene on to their children.”
Blood tests are used to determine whether a relative with cancer has the faulty gene, and if so, whether this is shared by an as yet unaffected relative. Finding the same gene is described as a positive result, meaning that the person has an increased risk of developing cancer. It does not mean that they have cancer or will definitely develop it.
My mum was the first woman in the family to be affected by such a disease so there is no evidence of a genetic link. But the idea that we could identify future health complications early on is timely. The Genomic Risk Score (GRS) has recently been announced which, for £40, could identify if a person is predisposed to heart disease.
Dr Rawlins says they get around five to 10 genetic tests a month at the NNUH – but that only a couple of these will be positive. “A lot of patients tell us they want to know for their families’ sake. We don’t push the genetic testing on patients, we simply talk about what it could mean for them and their families if an abnormal gene was found, and then allow them to choose if they want to know. The vast majority of patients who are offered testing do take it up.”
The main advantage of taking a genetic test is the ability to make an informed decision about the future. “Patients who are gene carriers have three main options,” says Dr Rawlins. “They can do nothing, which rarely happens.
“They can have enhanced surveillance such as annual imaging to try and detect any problems early on. Younger women usually have an MRI and older, usually postmenopausal women have a mammogram.
“Or they can undergo risk-reducing treatment with drugs or surgery. Some patients opt for bilateral mastectomies where the breast tissue is removed. These can significantly lower the risk but do not eliminate it completely. BRCA carriers also have a higher risk of ovarian cancer so some ladies have surgery to remove their fallopian tubes and ovaries too. Where possible, reconstruction is offered to patients undergoing mastectomies.”
In most cases, a negative result is the most sought-after outcome – but occasionally, this can bring its own frustrations too. “On the one hand it’s good news if no gene is found, but also it means for some families we can’t give them an explanation for the number, or patterns of cancer in their family,” says Dr Rawlins.
“It may be that cancers are prevalent in a family not as a result of an abnormal gene, but simply due to a combination of bad luck and the fact that breast cancer is so common.
“The alternative explanation is that there may be genes that are as yet undiscovered or that there’s no test available for. The world of genetic testing is fast-moving and new genes are likely to be found in the future.
“There is a third outcome, which is where an alteration is found in one of the breast cancer genes, but it’s not known if the alteration is cancer causing.”
The downside of getting a positive result lies in its unpredictability. As it doesn’t indicate that you will definitely develop cancer – only that there is an increased probability – knowing that you have inherited a faulty gene could lead to increased anxiety, depression and anger and have a negative impact on your day-to-day life – as well as your family’s.
But as you face such a decision, help is available. “Whether to go ahead with breast cancer gene testing is a very personal decision,” says Sam Glee senior cancer information clinical nurse specialist at Big C.
“Our specialist team at Big C is available to talk to anyone considering breast cancer screening, or their family, and can help with any further information they may require. We can also help those who may have received their results to understand what it means for them and offer emotional support.”
Speak to your GP to find out more about genetic testing and if it applies to you. For more support, advice and information, you can also visit the Big C website or call the Big C telephone support line on 0800 092 7640.
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