Ask the Expert: Do Our Genetics Hold the Key to Cancer Treatment?

Kristen Whitaker, MD, Assistant Professor of Clinical Genetics and Medical Oncology at Fox Chase Cancer Center, explains that while there are still some unknowns about breast cancer, genetic mutation might hold some of the answers. 

Q: How big of a role do genetics play with breast cancer?

A: Five to 10 percent of breast cancers are caused by mutated genes. BRCA1 and BRCA2 mutations are the most common cause of hereditary breast cancer. People often assume that number is higher, but we don’t know what causes most breast cancer. In about 20 percent of cases, women have what’s called familial breast cancer. This means we see a pattern of breast cancer in their families, but we can’t find a gene to explain it.  

Q: Who should be genetically tested? 

A: We haven’t reached the point where all women are tested. Today, the decision is based on several factors: Does a woman have a strong family history of breast cancer? Has a woman had a breast cancer diagnosis at a young age? Does a woman who has been diagnosed with breast cancer have a close family member with other cancers, such as pancreatic or ovarian cancer? If you have questions about genetic testing, a good place to start is your gynecologist or family physician.    

Q: What if a test comes back positive? 

 A: Knowing whether a woman has a genetic mutation that increases her risk of breast cancer changes a lot. First, it affects how closely and frequently we screen her in the future. We may also consider preventative options such as medications or mastectomy to reduce her risk of cancer. If the woman already has breast cancer, knowing her genetic profile also helps guide what treatments we offer and, in some cases, opens up opportunities only available for women with certain types of genetic mutations. 

Q: Where is the field of genetics headed? 

A: That’s a hot topic. Right now, we’re looking at who needs to be tested. Many feel we are missing women who could be at risk by not having universal testing. Studies are starting to show that family history alone isn’t enough to identify women with gene mutations. Over time, we may test all women. If we move in that direction, we will need many more genetic counselors to help guide patients through testing and education. This will help ensure appropriate management of genetic test results.

Q: What led you to specialize in genetics? 

A: My mindset has always been that preventing disease is better than a cure. Genetic testing empowers us to identify women at increased risk of breast cancer and potentially intervene to prevent it. I’m also interested in health disparities. African American women are diagnosed at similar rates but die more often from breast cancer than Caucasian women. We used to attribute that solely to socio-economic factors, but we’re discovering other factors like genetic differences that also may be driving this disparity.

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