RISK AND RISK REDUCTION > Established risk factors >
Family history
ESTABLISHED RISK FACTORS
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NON-MODIFIABLE RISK FACTORS |
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MODIFIABLE RISK FACTORS |
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FAMILY HISTORY
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
Some family histories suggest a genetic predisposition to breast cancer and related cancers. Such a family history may include the following on either the maternal or paternal side:
- 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.
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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