How Your Genes Affect Breast Cancer Care

Expert answers to common genetics questions

Mother and daughter in pink

With 230,000-plus new cases of breast cancer per year in the United States, there is a good chance someone in your family has been affected by this disease.

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As we learn more about the genetics involved, we know more about the role of family history — and how to diagnose and treat patients based on their specific needs. Below, breast surgeon Michael Cowher, MD, of Cleveland Clinic’s Breast Center, and I answer common questions about the genetics of breast cancer.

How has genetics changed the way surgeons approach breast cancer?

Dr. Cowher: Understanding the genetic factors for risk of breast cancer has moved family history to the forefront of the conversations surgeons have with breast cancer patients. It is important to identify patients at risk for hereditary breast cancer syndromes and promptly refer them for genetic counseling.

Dr. Eng: It has made surgeons and other doctors watch out for “red flags” of hereditary cancer, and that is a positive. These red flags can be everything from a family history of cancer to a diagnosis at a young age to having cancer in both breasts. Family and personal history are more important than ever.

It is important to identify these high-risk patients early so we do not delay their care.

When in the process do you typically see patients?

Dr. Cowher: Most patients come to me after an abnormal mammogram, having felt a breast lump, having nipple discharge or after breast needle biopsy. It’s my role to identify patients who may be at risk for a hereditary breast cancer syndrome. Rarely, a patient with a known genetic mutation will be referred to me from a geneticist — usually after someone else in his or her family has tested positive.

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Dr. Eng: This team approach is important. I always want to have a high-risk breast specialist involved when a genetic screening shows a mutation. And we always want patients to see surgeons like Dr. Cowher. This can be informative or actionable. It helps women make difficult treatment decisions.

Dr. Cowher: Frequently, genetic counseling is done immediately after an initial surgical consultation. Surgical plans — such as whether to undergo breast conservation (lumpectomy) or have a bilateral mastectomy — may hinge on genetic testing results. It is important to identify these high-risk patients early so we do not delay their care.

How do genetic screening results affect treatment decisions?

Dr. Cowher: Most commonly, patients with a hereditary breast cancer syndrome have a BRCA mutation, which confers a 60 to 80 percent lifetime risk of breast cancer. For these patients, we usually talk about bilateral mastectomy — although there are other options as well, such as increased surveillance.

Dr. Eng: We know there are 10 genes that play a role in breast cancer. BRCA1 and 2 are the most common and the ones most people know about, but then PTEN is right behind them. Knowing which gene is involved definitely changes the approach.

The type of genes also affects what types of cancers we watch for. With PTEN, for example, we look for thyroid cancer and other cancers such as uterine and colon, as well as breast cancer. Then there are much more rare genetic mutations such as CDH1, which is associated with lobular breast cancer. And NF1, which usually comes with skin changes in addition to the risk for breast cancer.

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Dr. Cowher: If a patient has one of these rarer genetic syndromes, I usually have a direct conversation with the geneticist to discuss an individualized treatment plan.

What do patients want to know after a positive genetic screening?

Dr. Cowher: Patients usually want to know their options — and the risks with each option. They also want to know the risks their family members may or may not have given this diagnosis. And they want to discuss prophylactic surgery, reconstructive options and alternatives such as increased surveillance.

Dr. Eng: Mostly they want to know what comes next. Because of genetic screening — and because of the team approach that involves geneticists, surgeons, oncologists and others — we can give them as much information as possible to make the best decision for them.

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Charis Eng, MD, PhD

Charis Eng, MD, PhD

Charis Eng, MD, PhD is founding chairwoman of the Genomic Medicine Institute and founding director of its Center for Personalized Genetic Healthcare. Dr. Eng is a global leader in cancer genetics and cancer genomic medicine.
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