About Breast Cancer>Testing>Genetics and family risk > Genetic test results and treatment decisions

Genetic test results and treatment decisions


Whether you are newly diagnosed or post-treatment, your genetic testing results may influence treatment decisions you make now or in the future. Positive, negative and uncertain results each affect decision-making in their own way.


If you test positive

If you are newly diagnosed, you may wonder how your treatment plan will not only treat the current cancer, but also help prevent a second, new breast or ovarian cancer. If you’ve completed treatment for breast cancer, you may already have taken some of these steps toward preventing a recurrence or a second breast cancer.


Double mastectomy

Some women choose to have both breasts removed in a bilateral mastectomy, also called a double mastectomy.

The decision to have a double mastectomy is very personal. Having the surgery may affect you physically as well as emotionally. Mastectomies are major surgeries and may require a good amount of rest and recovery. Removing your breasts also may cause worry or sadness over lost femininity or other body image concerns. Or you may welcome the idea of surgery because lowering your risk may rid you of some fears and anxieties.

If you were treated with a single mastectomy in the past and have just learned you have a BRCA mutation, it’s OK to talk with your doctor about removing the other breast. Depending on your level of cancer risk, the hormonal status of the cancer and your comfort, you may choose to have more screening tests or take hormonal therapy instead of having a risk-reducing mastectomy.


BRCA mutations are known to be related to an increased risk of both breast and ovarian cancer. In some families, there is also an increased risk of melanoma, pancreatic and prostate cancers. Studies have shown that the ovarian cancer risk is higher in people who carry BRCA1 mutations than in those who carry BRCA2 mutations.

Many women with mutations in either gene choose to have a risk-reducing salpingo-oophorectomy, surgery to remove the ovaries and fallopian tubes. The risk of ovarian cancer increases with age, especially after age 40.

Removing the ovaries greatly reduces the risk of developing ovarian cancer. It also stops the body from making estrogen, which fuels certain kinds of breast cancer. For some women, stopping estrogen production greatly lowers the risk of breast cancer recurrence. When done before menopause, oophorectomy also decreases the risk of a new breast cancer.

Talk with your doctor about the benefits, risks and timing of removing your ovaries before making a decision. When the ovaries are removed, you can no longer become pregnant naturally. Your body goes into surgical menopause, or menopause caused by the surgery. If you plan to have children in the future, you may wish to wait until later in your life to have an oophorectomy.

Hormonal therapy

Breast cancers in women who carry BRCA2 mutations are more likely to be estrogen receptor-positive (ER-positive) than in women who carry BRCA1 mutations. Hormonal therapy is medicine that blocks or lessens the amount of estrogen in the body so that it can’t fuel cancer growth.

If you have an ER-positive breast cancer, your doctor may recommend 5 to 10 years of a daily hormonal therapy pill. Which medicine you take will depend on your age and menopausal status. Taking hormonal therapy for 5, and sometimes 10 years, has been shown to reduce the risk of recurrence and second breast cancers.


If you test negative

If you test negative for a gene mutation already identified in your family, your result is considered a true negative. This result means you can feel confident following the standard breast cancer treatment and follow-up screening in national guidelines. Your risk of recurrence and of being diagnosed with a second, new breast cancer is the same as a woman whose family does not carry a BRCA gene mutation.

Some women will test negative for BRCA mutations despite a strong family history of breast and ovarian cancer. Your doctor may still suggest that you follow a screening schedule based on your family history of cancer and if you’re the first in your family to be tested for a gene mutation.


If you test inconclusive, uninformative, or show a variant of uncertain significance

If you receive one of these test results, your genetic counselor may recommend you have mammograms, clinical breast exams and gynecologic visits more often than women at average risk. If you’re young or at very high risk, your doctor may also recommend breast MRIs.

If your family has a strong history of breast or ovarian cancer, you are likely considered at “high risk” even though your test wasn’t positive. Talk with your doctor about the risks and benefits of surgery and other preventive measures.


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Reviewed and updated: August 31, 2015

Reviewed by: Mark Robson, MD


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