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Understanding breast cancer genetic testing

March 17, 2020


Understanding breast cancer genetic testing

More than 3.1 million women in the U.S. have had breast cancer or are currently in treatment. Though studies indicate the average woman has a 1 in 8 lifetime risk of developing the disease, individual risk varies according to family and reproductive history, lifestyle, and more.

About 5 to 10 percent of all breast cancers are linked to a mutation (change) in genes that's passed down in families.

Though many inherited gene mutations increase breast cancer risk, the most common are the BRCA1 and BRCA2 genes. People who inherit a gene mutation associated with breast cancer are also more susceptible to ovarian, pancreatic, prostate, and skin cancers.

Cancer family tree

Meredith Cashdollar, Certifi ed Physician Assistant at WellSpan Breast Care, helps patients understand inherited cancers. Along with her patient-care responsibilities, she provides genetic evaluations for patients diagnosed with breast cancer and those concerned about cancer risk.

During an initial patient consultation, Cashdollar creates a three-generation pedigree. This family tree outlines parents, siblings, and ancestors, their known cancers, and ages at diagnosis and death.

"Age is a big predictor of cancer risk," she says. If a patient's completed pedigree matches National Comprehensive Cancer Network (NCCN) guidelines (see sidebar), Cashdollar recommends genetic testing as the next step.

Twenty years ago, BRCA1 and BRCA2 were the only known genes to be tested to assess breast cancer risk. Technology has advanced so much that multi-gene panel testing is now available to those who qualify.

Cashdollar performs genetic testing at the WellSpan Breast Care office in Chambersburg. Before the test is performed, Cashdollar details the process.

"I tell patients what genes I'm testing for and their links to specific cancers. I explain medical management that might be needed if there's a positive result. We discuss insurance coverage and ramifi cations for family members who may need to make their own decisions about testing.

"Cost is the number one reason patients don't choose genetic testing," says Cashdollar, noting that most insurance plans now cover the test. If there is an out-of-pocket cost, it's less than $300. "That's comparable to direct-to-consumer DNA tests that only look at tendencies and can give false assurances," she says.

In addition to determining risk, genetic testing helps doctors decide the best treatment for patients. Cashdollar recalls a 48-year-old female patient with invasive ductal breast cancer who opted for genetic testing after completing chemotherapy and radiation.

"She thought her cancer was taken care of, but then tested positive for the BRCA1 gene. Her treatment team recommended a bilateral mastectomy and removal of ovaries and fallopian tubes. Without testing, she never would have known she was at high risk for recurrent breast cancer and ovarian cancer."

What about men

The misconception that men can't carry mutations that increase their risk of breast cancer often deters them from being tested. Fortunately, that wasn't the case for a 39-year-old man who came to see Cashdollar after his sister was diagnosed with breast cancer and tested positive for the BRCA2 gene.

"Siblings have a 50 percent chance of being carriers," says Cashdollar. "The brother also was found to have inherited the BRCA2 mutation, placing him at higher risk of developing male breast cancer, prostrate, pancreatic, and skin cancer."

Knowledge is power

Learning you have a heightened risk of a serious disease can be worrisome, but it also can be empowering.

Cashdollar helps patients develop proactive and personalized approaches to dealing with risk.

"We follow patients for years--seeing them more often and providing more and different types of screenings and medical management," she says.

Backed by government and medical communities, genetic testing continues to evolve. The Genetic Information Nondiscrimination Act (GINA) prevents insurers from denying coverage or charging higher premiums when genetic mutations put people at higher risk for diseases.

In February 2019, the American Society of Breast Surgeons called for widening recommendations for genetic testing for breast cancer to encompass a larger population.

"Genetics is a rapidly changing field and testing is only as good as the current year," says Cashdollar. "I tell my patients that new genes are being identified all the time. That means more lives will be saved."

Who should get genetic testing for breast cancer?

Genetic testing should be done in a medical setting after discussing benefits and risks with a trained health care provider. Testing may be appropriate if these apply to you or your family:

  • Breast cancer before age 50
  • Known BRCA1 /2 mutation or other inherited breast cancer gene
  • Multiple relatives on the same side with breast cancer
  • Multiple breast cancers in the same woman
  • Both breast and ov arian cancer
  • Ashkenazi Jewish descent
  • African American diagnosed with breast cancer before age 35
  • Ovarian, pancreatic, prostate, melanoma, or male breast cancer