Dr. Terpenning shares what a woman should know about genetic testing for breast cancer.
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What Should Women Know About Genetic Testing For Breast Cancer? Dr. Marilou Terpenning: Women should understand the genetic testing for breast cancer, and there’s often a point of confusion for women that what women think of is genetic testing can be two different types of testing. Genetic testing is accurately described as testing for any mutations that a woman might have in her own genome that would predict that she has an increased risk for developing cancer. So, that’s what we are going to talk about, and most commonly screen for breast cancer precursing gene mutation or mutations in the BRCA genes and chromosomes 13 and 17. There are other mutations that are present but those are the ones that we will talk about. As an aside, I would just close my initial comments by saying that I often get asked the question about genetic testing for women when they are getting HER2 testing done, which is an acquired gene mutation, not a hereditary gene mutation. So, it’s two different types of genetic testing. One is the test on the cancer; one is the test on a person. So, the BRCA testing is a test on a person on blood, and we are taking a look to see if a woman carries mutation, a deleterious mutation in BRCA 1 or 2 gene. This will predict for an increased risk for breast cancer. Things that might make you think that you should be tested are if you have a family history of breast cancer, particularly if you have a family history of breast cancer in a mom, in a grandmother, in a maternal or paternal aunt, in your father, because men can get breast cancer when they carry BRCA mutations, and your father’s mother, or obviously in your siblings. Another thing that would tip you to getting BRCA testing is if you get a young breast cancer; if you have breast cancer in your 30s or early 40s. Then even if there is no family history, you may be a candidate for BRCA testing. Some families don’t have good, what we call family pedigrees which is the whole outline of a family history, and BRCA mutations can be carried through the male line, not just the female line. That’s not commonly understood. Many women feel, “Well, my mother didn’t have breast cancer, so I am fine.” It can come through the male line and because men don’t get breast cancer commonly, we won’t see it in the father. We may see prostate cancer because that’s part of the BRCA complex. So, particularly in a woman who is a young woman with breast cancer, who has a father with prostate cancer and his mother had breast cancer, we’d be very suspicious that there could be a BRCA mutation in that family. Also, individuals of certain ethnic background with young cancers, individuals of Ashkenazi Jewish background, of Dutch background, of Icelandic background, Celtic background. There are many different mutations that have been defined in BRCA. BRCA mutations that have been defined that are population restricted based upon founder gene effects in small, insulated populations like Jews in central Europe, in the Middle Ages, people in Iceland. The gene got amplified throughout the population or spread throughout the population, so you will see high incidences in BRCA mutations in those groups of women. So, for a woman who is newly diagnosed checklist mentally is, “If I am young, under 45, and if anyone in my family has had breast cancer, I’d better ask the doctor about it.” Most doctors are getting pretty good about screening for this and asking the questions, but you can’t count on that. You want to be assertive about that because it’s important and it will help with your decision-making. For example, I had a woman who I treated 15 years ago for a breast cancer and I did an MRI on her and found a small, new cancer in the same breast, which is very unusual. That’s often a tip-off to BRCA mutation. She had absolutely no family history of malignancy. I did BRCA testing and she was positive. Her first breast cancer had been at 42; her second one was at 55, and she is of Ashkenazi Jewish decent.
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