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Q&A: What You Need to Know About Genetic Testing for Breast Cancer


For those with a history of cancer, especially breast cancer, genetic testing can be a positive way to take early action or learn more about genetic makeup and associated risks. While some individuals do not wish to know their risks, for others, it has the potential to save lives. Kim McGreevy, a certified genetic counselor at Chester County Hospital in West Chester discusses the process of genetic testing for breast cancer and what patients can expect.

MLT: What do you look at in patients considering genetic testing?

KM: I look at their personal history, their family history, how likely it is that their family history is hereditary, and then we can test to see if that’s correct. We just need a DNA sample—saliva or blood—and we just need to tell the lab which gene to test for. We think about five to 10 percent of people that get breast cancer is due to a mutation in one specific gene, and that’s called hereditary breast cancer.

MLT: Who should consider genetic testing?

KM: Anyone that meets the NCCN guidelines. In general, people who have early on-set breast cancer—meaning anyone diagnosed under the age of 45; people who have had ovarian cancer; people who have a strong family history of breast or ovarian cancer—meaning two or more relatives on the same side of the family; Ashkenazi Jewish individuals; and males who get breast cancer.

MLT: Who gets tested?

KM: We like to test somebody who has already had cancer, and then only test the other relatives if the initial family member is found to have a mutation.

MLT: What does genetic testing look to find?

KM: With clinical genetic testing, they’re looking at known genes that are predisposed to cancer. They’re looking to see if someone has that mutation in the gene that would shut the gene down.

MLT: How is this information evaluated?

KM: Labs do the testing and they interpret whether the gene is completely normal or has a mutation that’s known to be associated with the disease. Sometimes they’ll find a variant, where they’re uncertain. [With variants] some labs leave it up to counselors.

MLT: When should somebody consider genetic testing?

KM: For genes related to breast cancer, especially BRCA 1 and BRCA 2, we usually don’t start testing until mid to late 20s. Even if you carry a mutation, we don’t do screenings until that age—there’s not a need to know before then. We’ll also recommend testing five to 10 years before the youngest occurring age of cancer in the family.

MLT: How long can patients expect to wait to hear their results?

KM: It can take between two and four weeks.

MLT: What happens after you get your results?

KM: Patients usually come in for a follow up to go over the results, but also meet with a physician who is board certified. It’s a team approach. We come in and go over the results, and I interpret the genetic side of things, and we make recommendations. We refer them to other doctors, as needed, to discuss options. We map out the guidelines for them.

MLT: What are some of the concerns for patients considering genetic testing?

KM: Before the [Genetic Information Nondiscrimination Act of 2008,] people were worried about genetic discrimination. Mostly, they want to know the information, but are worried about how it would affect their children or grandchildren, especially moms. There’s sometimes a lot of guilt that they could pass this on to their kids. They are hesitant to find that out.

MLT: How do you recommend talking about family history?

KM: Knowing your family history is really key. People don’t know that as well as they should. Ask family members about cancer histories. Break down that barrier of not wanting to talk about cancers. If we know there’s a strong family history, we can hopefully be preventive or catch it early.

MLT: What’s the benefit of meeting with a genetic counselor?

KM: Genetic testing can be done through many different ways now. I do think patients can get a lot out of meeting with a genetic counselor so they understand their options and the implications of the results. It gives them a better understanding of the process and purpose.

Kim McGreevy