Breast Cancer

Genetic Testing for Hereditary Breast Cancer

Although many women with a family history of cancer worry about hereditary risk, most cancers – even those within a single family – occur simply by chance. In fact, only 5 to 10 percent of cancers are strongly linked to inherited genetic mutations (abnormalities).

Mutations in the BRCA1 and BRCA2 (breast cancer 1 and breast cancer 2) genes were among the first cancer-related gene mutations to be identified. These mutations increase the risk for breast cancer as well as ovarian cancer and cause a condition known as hereditary breast and ovarian cancer syndrome.

In 2013, the U.S. Preventive Services Task Force recommended screening to identify women who have family members with cancer of the breast, ovary, fallopian tube or peritoneum and may be at increased risk for BRCA1 and/or BRCA2 mutation. This recommendation is designed for women who have not received a diagnosis of breast cancer. Two national cancer organizations, the American Society of Clinical Oncology and the National Comprehensive Cancer Network, recommend genetic counseling for people who are considered to be at high risk for hereditary breast cancer.

About one in five women with breast or ovarian cancer is a candidate for genetic evaluation and possible genetic testing. Several “red flags” are strong indicators that you should talk to your doctor about genetic counseling, which should always be done before and in conjunction with genetic testing (Table 1). Genetic counselors can help you better understand your risk for breast and/or ovarian cancer and how genetic testing will affect you and your family. Counselors can also discuss options to reduce the risk of cancer if a mutation is found.

For women with breast cancer, the identification of the BRCA1 and/or BRCA2 abnormalities may indicate a 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 undergo a preventive mastectomy of the opposite breast (or both breasts) or remove their ovaries to reduce the risk of a second breast cancer or ovarian cancer. These procedures are associated with substantial side effects, such as negative body image, the inability to have children, potential risks to bone and heart health, and early menopause. These must be weighed against the potential benefits of preventive surgery.

Other women choose a chemoprevention approach, which involves taking hormone therapy drugs for five to 10 years in addition to regular screening mammograms or other imaging procedures.

Women who decide against preventive surgery or chemoprevention should still be screened regularly for the early detection of an additional cancer that might develop.

Identification of hereditary breast cancer is now becoming important in treatment decisions. Studies have shown that tumors with BRCA1 and/or BRCA2 mutations have distinct characteristics that may make some types of targeted therapy more effective than traditional treatment strategies. In addition, studies of hereditary ovarian cancers have suggested that specific chemotherapy agents may be more effective. 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 because there is a 50-percent chance of a mutation in a first-degree relative (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 is usually the most expensive, but once a mutation is identified in a family, the cost drops significantly for relatives who subsequently have testing. Medicare and private health insurance cover testing in most cases, but always investigate your insurance coverage first. Some testing laboratories are also able to help verify insurance coverage before testing is done.

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 by the age of 50?

Was anyone in my family diagnosed with breast cancer by the age of 50?

Do I have triple-negative breast cancer?
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 been diagnosed with two breast cancers or breast and ovarian cancer?
Has anyone in my family been diagnosed with male breast cancer?
Do I have a family member who had breast cancer with one or more of the following: thyroid cancer, sarcoma, adrenocortical carcinoma, endometrial cancer, pancreatic cancer, brain tumor, diffuse gastric cancer or leukemia/lymphoma?
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)?

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