How genetics affects your breast cancer risk

Sep 06, 2018

One in eight American women will develop breast cancer at some point in her lifetime. Although medical researchers do not yet know what causes the disease, a number of factors can affect your chances of getting it.

Risk factors include lifestyle choices such as your eating habits, level of physical activity, and whether you smoke. Risk factors beyond your control include your age; past exposure to a mantle radiation used to treat lymphoma; and the ages at which you had your first period, delivered your first baby, and went through menopause.

For a small percentage of women, a family history of breast cancer—having at least one blood relative who has had breast or ovarian cancer—can increase the likelihood of developing the disease.

Only 5 to 10 percent of women diagnosed with breast cancer have inherited one of the damaged genes associated with it. These genes are associated with ovarian, pancreatic, and prostate cancers, as well. But because inheriting these mutated genes can significantly increase the risk of contracting breast cancer, it’s worth talking to your doctor if you are concerned about your own family background.

Determining Your Family-Related Risk

When doctors look at family history from a genetics standpoint, they consider both the paternal and maternal sides of the family, for three generations. Although more family members with breast cancer means more risk, determining familial risk is not merely a matter of tallying up the number of relatives who have been diagnosed with the disease. Generally, cancer in first-degree relatives (parents, siblings, and children) affects your risk the most.

Having breast and ovarian cancer in your family also amplifies the risk, as does having a relative who was diagnosed when younger than 50. If a man in your family has gotten breast cancer, that augments the risk, as does a relative who had cancer in both breasts. The particular type of breast cancer your relatives had is a factor as well.

Genetic Counseling and Testing

Your health care provider can review your family history with you and may refer you to a genetic counselor. If that happens, it does not necessarily mean that you are high risk; it just means that it’s worth looking deeper. Counselors can provide information about managing cancer risk and more detailed information about the genetics of breast cancer.

Genetic testing is also something to consider if you are found to be at high risk. Whether to have genetic testing is a deeply personal decision because the results can have an emotional impact for you and your family.

Genetic testing for breast cancer involves a blood test that looks for mutations (harmful alterations) in specific genes. For more effective testing, it is helpful if a relative who has had breast cancer gets tested first; then geneticists can find the particular mutation that relative has and know specifically what to look for in your sample.

Remember that family history is just one piece of the puzzle. By maintaining a healthy lifestyle, getting regular screenings, and paying attention to your breast health, you should be able to give yourself the best possible chance to stay cancer-free. To find out more about managing your risk for breast cancer, click here.

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