Family History and Genetic Testing
Family History of Breast Cancer
Breast cancer is one of the most common cancers to affect Australian women, with 1 in 8 women having a diagnosis of breast cancer by 85 years of age. Because the disease is so common, many people have someone in their family who has had a diagnosis of breast cancer.
Rarely, breast cancer can develop as a result of a faulty gene which is inherited from one generation to the next. This accounts for 5% of breast cancer cases. The inheritance of a faulty gene can occur through a mother’s or father’s lineage. Occasionally a person may be the first in their family to have a faulty gene. Such genes may be associated with other types of cancer, particularly ovarian cancer and cancer of the fallopian tube.
There are particular aspects of a person’s history which increases the suspicion there may be an inherited faulty gene at fault for a breast cancer including a strong family history, multiple relative on the same side of the family with breast and/or ovarian cancer, breast cancer diagnosed in a young woman, men in the family with a breast cancer diagnosis, breast cancer in both breasts, particular types of breast cancers namely the ‘triple negative’ subtype and families with Ashkenazi Jewish heritage.
95% of women are at average or population risk of developing breast cancer.
4% are at ‘moderate risk’ of developing breast cancer.
1% is at high risk of developing breast cancer.
Family history plays an important role in determining which risk category you fall into. In addition to family history, there are several online risk calculators you can use to calculate which risk category you fall into, what your breast screening regime should be and what steps you can take to decrease your breast cancer risk. These include:
iPrevent Risk Calculator Tool developed by the Peter McCallum Cancer Centre, Melbourne
(First degree relative are brother and sisters, children and parents).
(Second degree relative include aunts, uncles, grandparents, nieces and nephews).
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95% of women are in this group. Most women (90%) in this category will not develop breast cancer.
No family history of breast cancer
Family history of breast cancer in:
One first-degree relative at age 50 or older, or
One second-degree relative at any age, or
Two first or second-degree relatives over the age of 50, on different sides of the family, or
Two second-degree relatives on the same side of the family, both with breast cancer at age 50 or older
Women with a Category 1 risk should be ‘breast aware,’ report any new symptoms to their doctor promptly and have screening mammograms every 2 years from the age of 40 or 50.
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4% of women are in this group. The risk of developing breast cancer is moderately increased compared to the general population.
One first-degree relative before the age of 50, or
Two first-degree relatives on the same side of the family, or
Two second-degree relatives on the same side of the family with at least one diagnosed under the age of 50Women who have a Category 2 (moderate risk) may choose to increase the frequency of screening mammogram and commence screening at a younger age. They should seat screening mammograms at the age of 40, or 5-10 years younger than the age the youngest relative was at the time of her breast cancer diagnosis e.g. a sister was diagnosed with breast cancer at 42 years old. Screening should commence at 32-37 years of age.
Women in this moderate risk category may also consider taking risk reducing medication such as tamoxifen. They may also wish to discuss their risk with a breast cancer specialist or seek a referral to a family cancer clinic.
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1% of women are in this group. The risk of developing breast or ovarian cancer is higher compared to the general population.
varian cancer is higher compared to the general population.
Two first or second degree relatives on the same side o the family plus;
One of more of the following features: additional family members with breast or ovarian cancer; a relative diagnosed with both breast and ovarian cancer; breast cancer diagnosed before the age of 40; breast cancer affecting both breasts; Ashkenazi Jewish heritage; breast cancer in a male relative.
A relative who has tested positive for a high-risk gene mutation e.g. a mutation in genes such as BRCA1 or BRCA2.
Women who have Category 3 (high risk) should follow recommendations for screening as outlined for women in the ‘moderate risk’ category. In additional they should consider referral to a family cancer clinic and may wish to discuss potential genetic testing. Risk reduction strategies including surgery and medication are also an option.
Recommendations for breast cancer screening will depend on which risk category a woman falls into. Regardless, all women are recommended to be ‘breast aware’ and to perform breast self-examinations regularly, see a doctor immediately to report any new symptoms and have a screening mammogram every 2 years from the age of 40-50.
Genetic Testing for Breast Cancer
In some cases, breast cancer is linked to specific inherited genetic faults. The most well-known mutations are in the BRCA1 and BRCA2 genes, which significantly increase the risk of breast and ovarian cancers. Genetic testing can help identify if you carry these or other mutations linked to breast cancer and testing is only done under the supervision of a specialist as there are pros and cons to testing and these need to be discussed prior to testing.
What Does Genetic Testing Involve?
Consultation: First, you will meet with a genetic counselor or specialist to discuss your family history and the potential risks and benefits of genetic testing.
Testing: The actual test is usually done through a blood or saliva sample, which will be analyzed in a laboratory to check for mutations.
Results and Counseling: Once you receive your results, a genetic counselor will explain what they mean for your personal risk and your family’s risk. Depending on the findings, your doctor may recommend enhanced screening or preventive measures.
Benefits of Genetic Testing
Personalized Risk Assessment: Knowing your genetic status can help your doctor tailor a screening plan, which may include starting mammograms or MRIs at an earlier age or more frequent screenings.
Informed Decision-Making: If a genetic mutation is found, you can consider preventive measures such as enhanced screening, medication, or even surgery (such as prophylactic mastectomy).
Family Awareness: Your results can provide valuable information for other family members who may also benefit from genetic testing or closer monitoring.
Considerations and Limitations
Genetic testing doesn't guarantee a cancer diagnosis or prevention; it only assesses risk.
Testing may have emotional and financial implications, and health insurance coverage for testing can vary.
A negative test result doesn’t eliminate your risk of breast cancer, especially if there is a significant family history. Other factors like lifestyle, environment, and non-genetic risk factors also play a role.
Next Steps
If you are concerned about your breast cancer risk due to family history, speak with your healthcare provider or a genetic counsellor to discuss whether genetic testing is right for you. Based on the results, your care team can help develop a personalized risk management plan that may include early detection strategies, lifestyle changes, or preventive treatments.
Key Points to Remember
Family history is important in assessing breast cancer risk.
Genetic testing can identify inherited mutations linked to breast cancer, although these genetic faults are rare.
If you have further questions or would like to explore genetic testing, please schedule an appointment with your healthcare provider.