Breast Cancer: Do Your Genes Put You at Risk?
Do your genes put you at risk for breast cancer? Our experts discuss.
Chances are you or someone you love has been affected by breast cancer. It is the third most common cancer in the country, with 200,000-plus new cases diagnosed each year.
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But did you know that many of those cases are tied to genetics?
“Ten to 15 percent of all breast cancers, which is a lot, are due to strong genetic causes that can be inherited and passed on,” says Charis Eng, MD, PhD, a geneticist and chair of Cleveland Clinic’s Genomic Medicine Institute and director of its Center for Personalized Genetic Healthcare.
The good news is that genetic counselors can help assess your risk. And it’s not future science — it’s available now.
“Genetic testing can tell you whether you have inherited a gene associated with increased breast cancer risk,” says oncologist Halle Moore, MD. These tests can tell if you have mutations of certain genes that cause cancer to grow faster than usual.
You may have heard of mutations in the BRCA1 and BRCA2 genes. They are the most common — and most commonly discussed — genes associated with breast cancer. But Dr. Eng points out that 10 genes are known to increase your risk of cancer. That includes PTEN, a gene she discovered that is linked to thyroid and other cancers, too.
“A PTEN mutation increases lifetime breast cancer risk to 85 percent, compared to 13 percent in the general population,” Dr. Eng says. “We were shocked to learn this. It means we have to do the same type of intensive screening as we do with BRCA1 and BRCA2.”
Dr. Eng points to seven red flags that suggest potential genetic breast cancer:
1. You have a family history of breast and/or other cancers. If cancer runs in your family, talk to your doctor about genetic counseling. Certain family factors — including the other red flags outlined below — may put you at greater risk.
2. You get breast cancer before age 50. Breast cancer is more common in women after age 55 or 60. Being diagnosed at a young age means you may have a higher risk of getting breast cancer again later in life.
3. Your breast cancer is a specific type. For example, “triple-negative” breast cancer is associated with the BRCA genes. “When we see a patient with a triple-negative breast cancer, we often recommend genetic counseling. We know those cancers have a higher likelihood of being hereditary, even if there’s not a big family history,” Dr. Moore says. A different type of breast cancer, lobular, is associated with stomach cancer and is caused by the CDH1 gene.
4. You develop cancer in both breasts. Getting cancer in one breast is common enough, but having it in both breasts is a sign of extremely high risk, Dr. Eng says.
5. You get breast cancer at any age but have one other risk factor, such as:
6. You have both breast and another type of cancer. For example, breast and ovarian cancers are often linked, especially in people with BRCA mutations. Dr. Eng says that having breast cancer with additional types of cancer can be a red flag, too. For example, having both breast and thyroid cancers may mean you have a PTEN mutation.
7. One of your family members has a gene mutation. If a family member has a mutation that increases cancer risk, you should be tested too. This does not mean you will inherit the family mutation. You have an equal chance that it will be negative — in which case your risk is the same as the general population.
Genetic counselors will gather your personal and family history in detail and consult your doctor. If you seem to be at risk, they may test a blood sample. If they find mutations, they will tailor a screening and prevention plan for you.
“For example, if you find out you have a BRCA1 mutation and you have had breast cancer on one side, you are at such a high risk for cancer on the other side that you may decide to do a prophylactic mastectomy,” Dr. Moore says. “If, on the other hand, testing doesn’t reveal a mutation, your risk of breast cancer on the other side is lower, and preventive mastectomy wouldn’t be necessary.”
Knowing exactly which of the 10 breast cancer genes is involved is crucial because the recommendations for each are different, Dr. Eng says.
“Genes are like encyclopedias in which we’re trying to look for very small typographical errors, and we have 35,000 encyclopedias in each cell,” she says. “Genetic counselors and genetic physicians can help choose which encyclopedia to read and find those errors.”