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EARLY DETECTION > Genetic testing
GENETIC TESTING
Most (90-95%) breast cancer diagnoses appear to be unrelated to hereditary factors. However, recent research has determined that approximately 5-10% of breast cancer cases are due to hereditary factors.1 In particular, we now know that mutations in either the BRCA1 or BRCA2 genes are associated with an increased risk of breast and ovarian cancer.
The BRCA1 and BRCA2 genes play a role in regulating the normal growth of cells. Mutations in either one of these genes can interfere with this regulating process and lead to the uncontrolled cell growth that is a defining characteristic of cancer. It is estimated that women who carry a mutation in the BRCA1 or BRCA2 gene have a 50 – 85% risk of developing breast cancer.1
The identification of the BRCA1 and BRCA2 genes has made it possible to search for mutations in these genes. This gene testing is offered when a family history suggests a hereditary predisposition to breast and ovarian cancer. Such a family history may include the following on either the maternal or paternal side of the family:
- Family members diagnosed with breast cancer before age 35.
- Family members diagnosed with ovarian cancer at any age.
- Multiple family members diagnosed with breast or ovarian cancer.
- A male family member with breast cancer.
- Family members who have been diagnosed with breast cancer in both breasts or with breast and ovarian cancer.
- Ashkenazi Jewish ancestry.
If you are concerned about your family history, consider discussing your concerns with a doctor, who can help decide if a referral to a genetic counselling clinic is appropriate. A genetic counsellor can determine whether your family history meets the eligibility criteria for genetic testing.
If genetic testing is offered, the genetic counsellor can explain in detail the benefits and limitations of the test. The counsellor will also outline the implications of genetic testing with respect to family relationships, insurance issues as well as the emotional and psychological impact of receiving positive or negative test results. With this information, you can make an informed decision about whether genetic testing is right for you.
1 Olivotto I, Gelmon K, McCready D, Pritchard K, Kuusk U. Intelligent Patient Guide to Breast Cancer. 4th ed. Edwards C, editor. Vancouver (BC): Intelligent Patient Guide Limited; 2006.
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