A Family History of Breast Cancer
Women with inherited BRCA1 or BRCA2 genes have a higher risk of developing breast cancer. What does this mean?
Some women are genetically more at risk of developing breast and ovarian cancer than others. Here we explain what that means, how you can find out if you are a carrier of the BRCA1 or BRCA2 gene mutation and how it affects treatment.
In the United Kingdom, around 55,000 women are diagnosed with invasive breast cancer each year. Up to five per cent of them have inherited a faulty gene from one of their parents that increases their risk of developing breast cancer during their lifetime. This is generally known as being a gene carrier. But what does that mean in concrete terms? How would you know if you have a mutated BRCA gene? How does that affect the treatment recommended?
Which genes can increase the risk of developing breast cancer?
The most common inherited genes that increase the risk of developing breast cancer are the BRCA1(BReast Cancer1) and BRCA2 (BReast Cancer2) genes.
Women with a BRCA1 or BRCA2 gene mutation have a 45 to 65% chance of developing breast cancer by age 70 (compared to the 12.5 per cent lifetime risk for the average woman in the UK), according to Cancer Research UK. The risk of ovarian cancer is 30 to 50 percent in women with a mutated BRCA1 gene; in BRCA2 mutation carriers at about 20 percent. The risk of passing the genetic modification on to their children is around 50 percent.
Note: In addition to BRCA, there are other rare gene mutations that increase the risk of developing breast cancer. The most common of these is TP53 (tumour protein p53).
How is the altered gene identified?
- If breast cancer has already been detected, doctors establish if an altered gene is present by using a genetic test. To do this, a blood sample is taken and sent to the laboratory for DNA analysis. Testing is usually carried out at a genetics centre after genetic counselling. At some hospitals, the breast care teams may carry it out.
- If cancer has not been diagnosed but you have a strong family history of cancer, you may be offered genetic testing to see if you have inherited an altered gene.
Who should be tested?
A strong family history of breast and ovarian cancer may be an indication of inherited altered genes. NICE guidelines have been drawn up to establish when genetic testing is useful. These are based on current research and are updated regularly. Your doctor will use them to assess whether genetic testing would be appropriate for you.
Genetic testing can be useful for some women who have already been diagnosed with breast cancer if their history suggests they are gene carriers. For example, women who are diagnosed very young with breast cancer are often offered testing as carriers of a BRCA1 or BRCA2 altered gene because of the increased risk of ovarian cancer and up to five-fold increased risk of a cancer also developing in the previously healthy breast. If it identified that the gene and these higher risks are present, extra preventative screening can be recommended.
Important: Talk to your doctor if you are considering having a genetic test. Many women prefer to know whether they are carrying the altered genes or not. This way, they can inform themselves of their options. Some women with a higher risk even choose to have their breasts prophylactically removed (preventive mastectomy).
However, women also have the right not to be tested – for example, because they don’t think it is helpful to know that they have an increased risk of developing breast cancer. Therefore, the advantages and disadvantages of a genetic test should always be discussed with your medical team.
What happens if someone finds out they are carrying the BRCA1 or BRCA2 altered gene?
That depends on whether the woman has been diagnosed with breast cancer or not. There are several options:
Breast cancer has been diagnosed
The treatment for breast cancer in women with BRCA mutation is essentially the same as for sporadic breast cancer. There are, however, a few exceptions. Women who have breast cancer due to an inherited BRCA gene mutation have an increased risk of also developing cancer in the healthy breast and /or contracting ovarian cancer. Therefore, there are different treatment possibilities:
- Preventive mastectomy of the healthy breast and removal of the ovaries
The prophylactic removal of the still healthy breast (mastectomy) as well as the removal of the ovaries can reduce the risk of disease.
What you should take into account in your decision: Both interventions have profound consequences – the operations not only change your body, but also often affect your quality of life. For example, you can no longer become pregnant without ovaries and the procedure prematurely puts you into the menopause.
- Targeted treatment with PARP inhibitors
BRCA1 and BRCA2 are genes that make proteins that help repair cell damage. Women with BRCA altered genes are diagnosed with breast and ovarian cancer more often because the cells affected by the gene mutation are missing an important repair mechanism. PARP is a protein in our cells that helps damaged cells to repair themselves. If PARP is blocked by a PARP inhibitor drug, the BRCA1 and BRCA2 tumour cells are often not able to repair themselves and they die.
No breast cancer diagnosis
For women who have not been diagnosed with breast cancer there are different options for prevention.
- Close observation and early detection
It is recommended that women found to have the BRCA mutation undergo regular screening. They may have more frequent tests – palpation, mammograms or MRI (magnetic resonance imaging) scans to check for breast cancer; ultrasound to scan for ovarian cancer, and, possibly, cervical screening. The earlier a cancer is detected, the better it can be treated.
Note: The type of screening offered will depend on individual history and the national guidelines . A variety of factors including age and level of risk are taken into consideration.
- Preventive mastectomy and removal of the ovaries
The removal of both breasts (bilateral mastectomy) can reduce the risk of breast cancer and the mortality rate; the removal of the ovaries helps to reduce the rate of death from familial ovarian cancer. However, prophylactic removal also has side effects.
- Drug treatment
Depending on the type of tumour and test results, medication such as tamoxifen, raloxifene or aromatase inhibitors may be prescribed to inhibit the effect of the female sex hormone oestrogen. Studies have shown, however, that many women decide to stop taking preventative hormone therapy due to its serious side effects, which include symptoms of early menopause .
Important: The best prevention programme is the one that is adapted to the individual. Your doctor can give advice on choosing the one that is best for you.
I’ve been told I have BRCA mutation. Does that mean my daughter needs to be tested?
This is an individual decision, but if you have been told you have BRCA1 or BRCA2 mutation, a genetic test may be useful for your daughter as well. If the result is negative, you can breathe a sigh of relief. If it turns out to be positive, she can take steps to prevent the cancer occurring and take part in screening programmes that can identify any changes early. Another factor to be taken into consideration is your daughter’s age. As breast and ovarian cancer are adult diseases, and as the person undergoing genetic testing needs to be able to make their own decisions, it is generally only available to women over the age of 18.
Who pays for genetic testing?
In the United Kingdom, the NHS covers the cost of genetic testing when it is recommended in order with the NICE guidelines, for example, if there is a strong family history of cancer in your family or a faulty gene has already been identified in one of your relatives.