An Overview of BRCA – BReast CAncer Gene

What is BRCA?

BRCA stands for BReast CAncer gene. Everyone has BRCA 1 and BRCA 2 genes. They are important genes that stop the cells in our body from growing and dividing out of control. By doing this, the genes help to protect us from getting cancer. They are often referred to as tumour suppressor genes. Everyone has two copies of each of the BRCA 1 and BRCA 2 genes—one copy inherited from each parent.

Both men and women can inherit a fault in their BRCA 1 or BRCA 2 genes. A fault in the BRCA 1 or BRCA 2 gene means that the cells can grow out of control and this can lead to cancer developing.2

If you have one of the faulty BRCA genes, there is a 50% (1 in 2) chance you will pass this on to any children you have and a 50% (1 in 2) chance that each of your siblings also has it.9

• Most cancers are not linked to inherited faulty genes. Between 5 and 10 in every 100 cancers (5 to 10%) diagnosed are linked to an inherited faulty gene.2
• A fault in the BRCA1 or the BRCA2 gene can lead to an increased risk for female and male breast cancer, ovarian cancer (including fallopian tube and primary peritoneal cancers), and to a lesser extent other cancers such as prostate cancer, pancreatic cancer, and melanoma.10

People who have inherited a harmful change in BRCA1 or BRCA2 also tend to develop cancer at a younger age than people who do not have such a variant.2

Genetic test for BRCA

If you are worried about a pattern of cancer in your family, talk to your GP. If your GP thinks that there may be an inherited cause for cancer, based on your family history, they will refer you to a genetics clinic. The clinic will do a detailed review of your family history to find your level of risk and whether you and or your close blood relatives should be referred for genetic testing. The most useful way of carrying out genetic testing is to start with someone who had a diagnosis of breast or ovarian cancer. This is called a diagnostic genetic test and involves a blood test.

If a BRCA1 or BRCA2 alteration is found in the family, it may be possible to offer genetic testing to other family members including those unaffected by cancer, to check if they share this gene alteration. This is called a predictive genetic test.8

You will need a GP referral for public or private genetic testing in Ireland.

What is the risk for breast and ovarian cancer with BRCA1 or BRCA2?

The risks of developing breast and ovarian cancer are markedly increased in people who inherit a fault in their BRCA1 or BRCA2.2

• Risks for developing breast cancer with an alteration in the BRCA1 or BRCA2 gene:

– On average, between 11 –14% of females without a genetic alteration will develop breast cancer in their lifetime. This risk increases for females with a BRCA1 or BRCA2 fault. Most recent research shows that:

– 65 – 79% of females who have inherited a faulty BRCA1gene and

– 61 – 77% of females who have inherited a faulty BRCA2gene will develop breast cancer by the age of 805

– A large prospective cohort study of 6036 BRCA1 and 3820 BRCA2 female carriers (5046 unaffected and 4810 with breast or ovarian cancer or both at baseline) showed that breast cancer incidences increased rapidly in early adulthood until ages 30 to 40 years for BRCA1 and until ages 40 to 50 years for BRCA2 carriers

– This study showed that the cumulative risk for developing breast cancer in the opposite breast (contralateral breast cancer) 20 years after breast cancer diagnosis is 35%-45% for BRCA1 and 20%-33% for BRCA25

Managing your cancer risk with a BRCA1 or BRCA2 Alteration:

Individuals who have inherited a harmful change in BRCA1 or BRCA2 have several options for reducing their risk of cancer. These include enhanced screening, taking medication to reduce their breast cancer risk and risk-reducing surgery (sometimes referred to as prophylactic or preventive surgery).7

• Enhanced screening: Individuals who are confirmed as having a BRCA1 or BRCA2gene alteration are typically offered breast screening from the age of 308

– Most women will be offered regular mammograms(X-rays of the breast) and a breast examination by a specialist clinician.

– Sometimes the clinician will include ultrasound scans, or Magnetic Resonance Imaging(MRI) of the breast because breast screening with mammogram alone is difficult in younger women who tend to have denser breast tissue. Dense breast tissue (non-fatty tissue) looks solid and white on a mammogram. You cannot see through it. This makes the mammogram more difficult to read12

– There is no known effective ovarian cancer screening methods. You may beoffered an internal(transvaginal) ultrasound can every year and a blood test called CA125. This is the only method available at present, but these procedures are not proven to be reliable in picking up early ovarian cancer.

• Risk-reducing medications (sometimes called chemoprevention)

– Chemoprevention describes drugs that are used to reduce the risk of cancer developing. This is different from chemotherapy which describes drugs that are used in the treatment of cancer

– Two drugs have been recommended by the National Institute for Health and Care Excellence (NICE) – Tamoxifen and Raloxifene. Both these drugs have anti-oestrogen properties

– Women with a BRCA2 gene alteration who are considering chemoprevention should have a discussion with their doctor regarding the potential benefits and side effects. Chemoprevention is not recommended for women with a BRCA1 gene alteration because most women with a BRCA1 gene alteration develop a breast tumour that is not oestrogen sensitive, and there is no evidence that Tamoxifen or Raloxifene would reduce their risk of breast cancer11

Risk-reducing surgeries (sometimes referred to as prophylactic or preventive surgery

• Risk-reducing, or prophylactic, surgery involves removing as much of the “at-risk” tissue—that is, the tissue where cancer may develop—as possible11

Managing your risk of breast cancer:

• Women may choose to have both breasts removed(bilateral risk-reducing mastectomy) to reduce their risk of breast cancer
• Women who have risk-reducing mastectomies reduce their risk of developing breast cancer to less than 5% over their lifetime, which is less than the risk in the general population11
• Breast Reconstruction or Not: Breast reconstruction is surgery to make a new breast after removal of the breast, part of the breast or both breast (double mastectomy)
• The aim is to make a breast of similar size and shape to your original breast but they won’t be identical
• It is a personal choice to have reconstruction or not and it may not be suitable for all women. Some people choose not to have breast reconstruction
• There are several types of breast reconstruction. Some techniques use implants. Others use tissue from your body (tissue from your belly (abdomen), back, or thigh) to recreate the breast
• Your surgeon and breast care nurse will talk to you about all your options. They will explain the advantages and disadvantages to help you make the right decision for you13

Managing your risk of ovarian cancer:

• Surgery to remove the ovaries and fallopian tubes is called bilateral risk-reducing salpingo-oophorectomy13
• This surgery is carried out to reduce the risk of developing ovarian or fallopian tube cancer and lowers the risk to less than 5%
• There are studies looking at whether it is possible to remove the fallopian tubes first, and delay removing the ovaries until a later date, to prevent ovarian cancer11

– One of those studies is called PROTECTOR study but it is not open to people in the Republic of Ireland. It includes 42 hospitals across England, Wales, Scotland and Northern Ireland and recruitment is due to close in December 2024

Be Breast Aware and know the signs and symptoms for Ovarian Cancer

After a discussion with your doctor, you may decide that none of the above options are appropriate for you at this time. It may be that you are younger than the recommended age for surgery, or it may be that you wish to stay fertile as you have not completed your family. It is important to make the decision that is right for you, and this decision can be discussed with your doctor, nurse, or genetic counsellor at any time.11

It is important to be ‘Breast Aware’ as part of your surveillance and to know the signs and symptoms of ovarian cancer. Please visit the Marie Keating Foundation website www.mariekeating.ie for further information and to view a video on how to check your breasts for changes.

References available on request

Written by Bernie Carter, Assistant Director of Nursing, Marie Keating Foundation

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