We are born with two copies of each gene. Genes are packages of information or “blueprints” that affect what our bodies look like and how they work. We get one copy of each gene from our mother and one copy from our father. We have more than 30,000 different genes in our body. Sometimes a change takes place in a gene that prevents it from working properly. This change in the gene is called a “mutation”.
Two genes have been discovered that are important in the development of breast and ovarian cancer. They are called BRCA1 and BRCA2.
BR = Breast
CA = Cancer, 1 = first gene found, and 2= second gene found.
If a person has a mutation (change) in the BRCA1 or BRCA2 gene they have a higher chance of getting cancer of the breast or ovary. Males who have a changed BRCA1 or BRCA2 gene may have a higher chance of getting breast or prostate cancer. When we get a mutated gene from one of our parents, this is called an ‘hereditary’ cancer.
Hereditary cancer is not common. Out of 100 people with cancer of the breast or ovary, only 5 to 10 of them would have a cancer that was inherited through their parent.
There is an increased chance that a change in the BRCA1 or BRCA2 gene is present when the family history includes:
- Breast cancer at an early age (before age 35 or before menopause)
- More than one cancer found in the same person, particularly breast and ovarian cancer in women
- Male breast cancer
- Breast and/or ovarian cancer in many generations on one side of a family.
- “Papillary serous type” ovarian cancer at any age
- Breast or ovarian cancer in a person of Ashkenazi Jewish descent
If you or your doctor thinks that breast or ovarian cancer may be inherited, you can be seen in a genetics clinic.
A genetics clinic can provide you with information about genetics. An experienced genetic nurse or genetic counsellor will help you complete a detailed family health history. This history can help you learn what the risk of developing breast or ovarian cancer is for you, your brothers and sisters, and your children.
Sometimes a genetic test for BRCA1 and BRCA2 genes can be done on a blood sample. This is usually from a member of the family who has had a cancer of the breast or ovary. Each province has guidelines for genetic testing. The genetic nurse or counsellor will let you know if this test is available to you or your family members.
To help you decide if you should be tested, genetic counselling provides:
- Information about the risk of genetic testing
- Information about the benefit of genetic testing
- Information about the emotional impact of knowing you may have a greater chance of getting cancer
- Information about the effect of genetic testing on other family members
- Social and psychological support
Even if genetic tests are not done, you will be given information about what screening tests can be done to detect cancer early.