Breast Cancer
Genetic Testing & Hereditary Breast cancer
Women often think about genetic testing as a way to find out if they are at increased risk for breast cancer because other women in their family have had the disease. Most cancers—even those within a single family—occur by chance; only about 5-10% of cancers have been found to be strongly linked to inherited genetic mutations. But genetic testing may be appropriate for some women with a family history of breast cancer.
Abnormalities in the BRCA1 and BRCA2 (breast cancer 1 and breast cancer 2) genes were among the first cancer-related gene mutations to be identified. The presence of these mutations is referred to as hereditary breast and ovarian cancer syndrome because they increase the risk for both types of cancer. About one in five women with breast or ovarian cancer is a candidate for genetic evaluation and possible genetic testing.
The decision about whether to have genetic testing depends on your personal and/or family history. Several “red flags” are strong indicators that you should talk to your doctor about genetic counseling, which should always be done in conjunction with genetic testing (Table 1). Genetic counselors help individuals better understand their risk for cancer and how genetic testing will affect them and their family and can discuss options to reduce the risk of cancer if a genetic mutation is found.
If genetic testing identifies BRCA1 and/or BRCA2 abnormalities, you may be at higher risk for cancer in the opposite breast and/or cancer of the ovaries. This increased risk leads some women to choose more extensive surgical treatment to help prevent the risk of a second cancer. For example, some women wish to have prophylactic (preventive) mastectomy of the opposite (or both) breast(s) or removal of the ovaries (ovarian ablation) to reduce the risk of a second breast cancer and/or ovarian cancer. These procedures are associated with substantial side effects, such as negative body image, infertility (the inability to have children), potential risks to bone and heart health, and early menopause. These side effects must be weighed against the potential benefits of prevention surgery. Other women choose a “chemoprevention” approach, which involves taking hormone therapy for 5-10 years in addition to regular screening with mammograms. Women who choose neither prevention surgery nor chemoprevention should have close surveillance with breast cancer screening so that if a second cancer develops, it can be detected early, when the chance for cure is higher.
Identification of hereditary breast cancer is also becoming increasingly important as researchers evaluate tumors from women with BRCA1 and/or BRCA2 mutations. Studies have shown that these tumors have distinct characteristics, and because of this, some types of targeted therapy may be more effective than traditional treatment strategies. In addition, studies of hereditary ovarian cancers have suggested that particular chemotherapy agents may be more effective. Thus, the presence of either mutation may be another factor in personalizing breast cancer treatment. Several clinical trials are being done to evaluate the effectiveness of various new and established drugs for hereditary breast cancer.
If a genetic mutation is identified, your genetic counselor and doctor will strongly encourage you to share the results of genetic testing with your family, as there is a 50% chance of a mutation in a first-degree relative (a sibling, child, or parent). Except for conditions that cause childhood cancer, genetic testing is not done on young children; in the case of testing for BRCA1 and BRCA2, it is recommended that testing not be done until a woman is in her early 20s.
Genetic testing can be expensive, and the cost depends on several factors, including the complexity of the test and how many family members are tested. The initial testing done is usually the most expensive, but once a mutation is identified in a particular family, the cost drops significantly for relatives who subsequently have testing. In most cases, Medicare and private health insurance cover testing, but individuals who are considering testing may want to learn about their insurance coverage first. Some testing laboratories are able to help individuals verify their insurance coverage prior to starting testing.
Table 1. Red Flags for the Possibility of Hereditary Breast and Ovarian Cancer
| Red Flag |
Questions to Ask Yourself |
| Age at time of cancer diagnosis |
Was I diagnosed with breast cancer before the age of 50? Was anyone in my family diagnosed with breast cancer before the age of 50? |
| Family history |
Do I have more than one family member who has been diagnosed with breast or ovarian cancer? Has any woman in my family had two breast cancers or breast and ovarian cancer diagnosed? Or male breast cancer? |
| Identification of gene mutation in family member |
Do I have a family member who has been found to have a gene mutation associated with hereditary breast and ovarian cancer? |
| Ethnic background |
Does my ethnic background include Ashkenazi or Eastern European Jewish heritage? |
| Other cancers |
Was any woman in my family diagnosed with ovarian cancer (at any age)? |
Additional Sources of Information
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