Direct-to-Consumer Genetic Testing for Breast Cancer
Direct-to-Consumer Genetic Testing for Breast Cancer
Scott Steele: Butts and Guts, a Cleveland Clinic podcast, exploring your digestive and surgical health from end to end.
Hi everyone. Welcome to another episode of Butts and Guts. I'm your host, Scott Steele, the Chair of Colorectal Surgery here at the Cleveland Clinic in beautiful Cleveland, Ohio. And today, we're very lucky to have Dr. Holly Pederson, who's a staff physician, the Director of Medical Breast Services in the Breast Center at Cleveland Clinic, as well as an Associate Professor of Surgery at Lerner. So Holly, welcome to Butts and Guts.
Holly Pederson: Thanks so much. Thanks for having me here today.
Scott Steele: So we always like to start out with all of our guests by giving a little bit of background about yourself. So tell us where are you from? Where'd you train? And how did come to the point that you're at the Cleveland Clinic?
Holly Pederson: I am from California. I went to college at UC Santa Barbara and then did my medical school and residency training at UC San Francisco, and came to Cleveland in 1994 for the Cleveland Clinic.
Scott Steele: And you've been here ever since.
Holly Pederson: Been here ever since.
Scott Steele: My wife went to Santa Barbara as well, so that's high level training there. That's fantastic. So today we're going to talk a little bit about genetic testing for breast cancer. You obviously are the Director of Medical Breast Services. So can you just very quickly go at a 50,000 foot level, and start by explaining what is direct to consumer genetic testing?
Holly Pederson: So direct to consumer genetic testing has become increasingly popular over the last several years. This do-it-yourself format from home enables many people to feel that they are getting high grade, clinical quality genetic testing from home in the privacy of their own home, and getting the same information that they might from a doctor's office.
Scott Steele: So there's a lot of these things that we see in advertisement where you can find your DNA, and where you're from, and all these different ones. How does this specifically work with breast cancer?
Holly Pederson: So it seems fun. You want to find out your ancestry and where your roots came from, and they have now tossed in some health information, and that's very important information for patients to understand. In March of last year, the FDA approved for one company to test for the three most common BRCA mutations that are seen in the Jewish community. And so, many people who think that they may be at increased risk for breast cancer sign up for this test to find out if they're at risk for breast cancer. But there's a lot of problems with that.
Scott Steele: So we'll get into the problems in a second. Let's just kind of boil this down a little bit more. So you have a test. What does it involve? What do they do at home? Is this a blood test? Is it that a scrape their inner lining of their mouth, or what do they do?
Holly Pederson: So genetic testing can be performed in several different ways. The most common way is through blood, but it can also be done through saliva, and that's how it's done through the home genetic testing. You're born with two copies of every gene in your body, one from your mom and one from your dad, and these tests are aimed to look at changes in the DNA that you inherit from your parents. And so, these changes are present in every cell in your body and if you have a change in BRCA1 or BRCA2, you may be at increased risk in women for breast or ovarian cancer, and in men for prostate cancer and also male breast cancer.
There's also a small risk of pancreatic cancer. People who have those diseases that run in their family with, of course breast cancer being the most common, wonder if they're at risk, and genetic testing is a way to potentially find out if you're at very high risk.
Scott Steele: One of the things you had mentioned was that ... was something about the Jewish population only, is this for everybody, or just for the Jewish population?
Holly Pederson: You really hit on the key point here. And so 10% to 15% of breast cancers are truly hereditary, meaning that you inherited a change in a gene from one of your parents, but the remainder of breast cancers are not hereditary, and you may still be at increased risk. So number one, if you test negative for genes that cause breast cancer, you still should be followed at high risk if you have a strong family history. And two, this test is very, very limited. So the direct to consumer testing for BRCA only covers the three founder mutations in the Jewish population. And the reason why I mentioned that is because 1 out of every 40 people of Ashkenazi descent carry a mutation in BRCA, as opposed to 1 and 400 in the non-Jewish population. So it's a very important population to screen. But if you're not Jewish, this test will not help you. And if you are Jewish, there are a lot of other genes that potentially should be tested for, rather than just these three.
Scott Steele: So if you are non-Jewish, you can still take the test. It's just, it's a much lower risk that may come up as positive, and you still need to be screened anyway.
Holly Pederson: Right. So out of 2 million patients that signed up for this test, .1% of people tested positive. I don't think people understand that they aren't really getting true genetic testing with this, "home genetic test."
Scott Steele: So how readily available are these tests? You just go on the internet and get one? How do you go about accessing them, and are they expensive?
Holly Pederson: Yeah, so you go on the internet and get one. The prices do change all the time, but they're increasingly available to most people. And it's important to distinguish between what we've been talking about, this direct to consumer genetic testing, and something called consumer directed genetic testing. There are a couple of companies now that are actually offering an online version of real clinical grade genetic testing that can be counted on. Don't assume that all direct to consumer genetic testing is limited and possibly unreliable. There are some new tests coming out, and there will be more all the time, that may be useful for people.
Scott Steele: So when you talk about the accuracy of these type of tests, is it inaccurate, or is it just that it's, if you play the percentages play, the odds, it's just not necessarily going to be helpful?
Holly Pederson: Yeah, that's a great question. So it boils down to the kind of technology that they use to perform the test. And when genetic testing is done in the medical setting, the genes are actually sequenced carefully and double checked. And when you get a result back, you can count on it. With this type of technology that they're using in the direct to consumer world, they're only looking at what we call snips, these little pieces of genes around the genes, and it's not actually true genetic testing, genetic sequencing. And what we found is that about 50% of the results can actually be false positives, meaning you get a result back that says you have a bad gene, and it's not even real.
Scott Steele: So we talked a little bit about the risks or potential downsides that occur with direct to consumer genetic testing. What are some of the positive signs?
Holly Pederson: Well, people feel empowered to find out information about themselves by themselves and in a private way, but the problem is they don't really know what they're getting into. Sometimes they'll get more information than they bargained for, and they don't have anyone to talk to, a medical professional, after they get these results, especially if they're abnormal. It's a situation where medical professionals are really not involved. You don't have that genetic counselor who explains what the testing is about, how it's performed, when it will come back, what the possible results are, and what you'll do with the results.
The advantage of this test is really to screen the Jewish population for BRCA genes that are most common, but in a another large study that was presented at San Antonio last year, in December, a very large commercial company looked at BRCA mutations in the Jewish population, and 19% are not these three. We used to think that almost all the BRCA mutations in the Jewish population were these three specific ones, but now there are many more and there are actually 12 genes that can cause breast cancer, not just BRCA 1 and 2, and there are thousands of different BRCA mutations within just BRCA, not just these three.
Scott Steele: So are there any of the things that these currently available tests can test for, or is a just this type of thing?
Holly Pederson: Well there are other disease states that direct to consumer genetic testing companies are testing for, but that's not my area of expertise.
Scott Steele: So what do you see on the horizon or the future for direct to consumer genetic testing, specifically for breast cancer?
Holly Pederson: Yeah, so I talked a little bit about snips, and snips is something that I want people to really take note of, because we have really strong genes in our body that predispose to cancer sometimes, moderate risk genes that predispose to cancer. But there are over a hundred, maybe over 300 now, little changes in genes that are very common, present in more than 1% of the population, which by themselves don't really do much, but in combination can really predispose someone to breast cancer. Because up until now, 75% of breast cancers occur in women with no known risk factors. I mean, we really need to be figuring that out, and in my opinion, one large component to explaining that risk is going to be something called snip profiles, and that will be useful and important in my opinion going forward.
Scott Steele: So let's just say that I'm a woman out there that has a strong family history or are interested in genetic testing, and don't really want to do this direct to consumer, but wants to get more available on it. How do they go about that? Is there a place that they could come to see you or talk to a genetic counselor or anything to see if there's some other type of testing, or just some routine screening that they could get?
Holly Pederson: So Cleveland Clinic offers an excellent program in genetic counseling, and a patient can get a referral from any physician to go see a genetic counselor and discuss their risk. Because as I said, they may continue to be at risk, even if their testing is negative. And so often patients are referred to myself or my team in the breast center to manage risk, whether people have a genetic mutation or just a strong family history. Both are important and people shouldn't be falsely reassured by negative genetic testing, whether it be direct to consumer or through a clinical grade test.
Scott Steele: You spoke a little bit about men and having this, so can you talk a little bit about that? I mean, most people don't think of men when they think of breast cancer.
Holly Pederson: Most people don't think about men when they think about breast cancer, but I think men think about their daughters when they think about breast cancer, and I would encourage them to do so. So let's say a man, his mother had breast cancer at a very early age, he may be carrying a gene that's silent, because he is not going to get breast or ovarian cancer that he could pass on to his daughters. So primarily we see women in genetic counseling settings, because they feel that they are at risk. But we need to keep in mind that we get half of our genes from our fathers, and half from our mothers. And so if a man has a strong family history, particularly if he has daughters, he should consider counseling, and there are very high rates of prostate cancer associated with these genes, and so men should be aware as well.
Scott Steele: And also just to clarify, a man could get breast cancer as well.
Holly Pederson: Men can. It's a less than 1% chance in the general population, and somewhere between a 6% and 12% chance if you have a BRCA2 mutation. So it's still relatively low ,but important.
Scott Steele: Well that's very interesting stuff in this ever evolving field. And so we'd like to end up all of our guests with a couple of quick hitters. So tell me your favorite sport.
Holly Pederson: My favorite sport has got to be tennis. I grew up playing tennis, and the highlight of my career was going to Nationals with my daughter.
Scott Steele: That's fantastic, a California girl. So what's your favorite meal?
Holly Pederson: My favorite meal? Probably watermelon. I just like eating watermelon.
Scott Steele: And the last non-medical book that you've read?
Holly Pederson: Hmm, well it was kind of medical. It's called Left Boob Gone Rogue. And it was a very touching story, written by a psychiatrist who got breast cancer at a very early age, and really lived through her journey in a public way and recently passed away, and I would recommend that book. We often think about beating the disease, but I learned a lot from her in living with the disease.
Scott Steele: It sounds like an interesting book. And so finally, tell me one of the things that you like about living here in Cleveland.
Holly Pederson: I think the new, smaller restaurants that are popping up, I think is probably one of my favorite things, and the ability to get there on the freeway.
Scott Steele: Yeah, it's definitely different from the west coast. So for more information about breast cancer, download our free treatment guide at clevelandclinic.org/breast, that's clevelandclinic.org/breast. And to make an appointment with a Cleveland Clinic specialist, call our Breast Center at (216) 445-7946, that's (216) 445-7946. Holly, thanks for joining us on Butts and Guts.
Holly Pederson: Thanks so much for having me.
Scott Steele: That wraps things up here at Cleveland Clinic. Until next time, thanks for listening to Butts and Guts.