Genetic Testing For Cancer: Your Questions AnsweredFeb 5, 2014
If you have a family history of cancer, you may have considered genetic testing to see if you actually have the mutation that causes the disease. It’s a very useful tool, but there are many other considerations such as who should be tested, interpreting the results and what happens next.
In this interview, Dr. Saundra Buys from Huntsman Cancer Institute answers many questions you might have about genetic testing for cancer, including why you should consult with a genetic counselor first, the types of cancers that testing can effectively uncover and how that information can help you.
She also talks about a recent survey conduced by Harris Interactive for University of Utah’s Huntsman Cancer Institute that found 34% people surveyed would not seek genetic testing even if they had a family history of cancer. She’ll cover what the concerns are and other takeaways from the study.
Interviewer: Learn about one of the really exciting advances in cancer prevention and treatment. That's next on the Scope.
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Interviewer: Up until now, family history was one of the best predictors for developing cancer, but now there is something that's a lot better. Dr. Buys from Huntsman Cancer Institute. One of the exciting advances in cancer prevention and treatment is genetic testing for cancer. What makes it so effective?
Dr. Buys: Family history is really important in determining how likely you are to get cancer and that's absolutely true, and genetic testing can take it one step further. So if you have got a strong family history, can we identify the factor that gives you that strong family history? And if we can, then what that allows us to do is say, "Yes, your family has a high risk for getting cancer but person number one, you don't have that alteration and person number three, you don't have that alteration. So you, personally, don't have a higher risk."
It allows us to fine tune this family history and figure out why you have got a strong family history and who within that family does and does not have the high risk.
Interviewer: So, just because I have a family history, doesn't mean that I am going to get it, and this genetic testing could put met at ease?
Dr. Buys: That's exactly right. That's exactly right. What we know is that . . . let's use the example of breast cancer; we can use colon cancer or other cancers. If you have no family history of breast cancer, your risk is in the ballpark of 10%. If you have a strong family history of breast cancer, your risk may be 20% or 30%. But if you have one of these genetic changes then your risk maybe 60% or 70%, and if you are in the same family and you don't have the genetic mutation that causes the cancer, your risk would be back down to the 10% range.
Interviewer: So there was a Harris Interactive poll conducted for University of Utah Huntsman Cancer Institute. And in this poll, they found 34% of people would not seek genetic testing even if they had a family history of cancer. Of course, the good news is 66% would. But with this 34%, what was the problem? Because this sounds pretty good to me.
Dr. Buys: Well, genetic testing is pretty good but it's not for everyone. But what I learned from looking at that very interesting poll is that many people just need more education about genetic testing is and isn't and the pros and cons. So for example, of that 34% of people, a third of people who basically said that they wouldn't get genetic testing, the majority of them said they wouldn't get genetic testing because they were worried about insurance discrimination or employment discrimination. And it turns out that for a number of years there have been laws, both locally and nationally that prevent discriminations based on genetic testing.
I think it's fine for a third of people to say, "I have got a strong family history but I still don't want genetic testing," but I think they, hopefully, understand that they shouldn't avoid genetic testing because of risk of discrimination.
Interviewer: Or privacy concerns.
Dr. Buys: Or privacy concerns.
Interviewer: The other interesting thing I thought was, only 8% of the people that were surveyed have received genetic testing for cancer as of this point. That's a very low number. Do you feel that the number should be higher? Do you think more people should get tested?
Dr. Buys: I think that's probably a pretty reasonable number. So, if we look at everybody in the population, I think there are probably 10% of people who have a strong enough family history that it's worthwhile doing the testing. So it's not a test that everyone needs to do. It's not a test that would be valuable for most people.
The other thing I think was interesting in that poll is that of the 8% of people who said they had genetic testing, several of them said they have had genetic testing for a lung cancer and genetic testing for prostate cancer, and right now there are not good genetic tests for lung cancer and prostate cancer. So I think people are confused about what genetic testing is.
I think that probably some people said, "Yes, I have had genetic testing for prostate cancer," when actually what they had was screening with a P.S.A., prostate-specific androgen. And people who said they have had genetic testing for lung cancer, they might have had lung cancer and their cancer cells underwent testing to see whether there were some genes turned on or turned off that might make a difference in the treatment, which gets back to your earlier question.
So, I think that 10% of the population is roughly the right percent of population to have genetic testing, but I don't think that the people polled necessarily had actually had genetic testing based on the diseases that they had testing for.
Interviewer: So, prostate and lung, you said, not necessarily were not quite there yet. What are some that we are there?
Dr. Buys: Correct. Brest cancer, ovarian cancer, colon cancer, melanoma, some kind of pancreas cancer and some family settings, and then some unusual tumors like paragangliomas, adrenal cancers and sarcomas, when they occur in a familial cluster are other cancers that we have genetic testing for.
Interviewer: That are pretty good?
Dr. Buys: Yes. So most of the cancers, if we do genetic testing, we will not find a mutation, but maybe 10% of people or 5% of people, if we do genetic testing in the right setting, we will find the gene mutation that can then inform them on other risks and inform their family members about their risks.
Interviewer: So, I can see the double-edged sword of looking into the future, if you will. On one hand, I might want to know that I am going to be one the family that might be predisposed to it. On the other hand, I might not want to know because what can I do about it? Let's talk about those people who think, "What can I do about it?" Could genetic testing really help them?
Dr. Buys: Oh, yes. People who are found to have genetic mutations that increase the risk of, for example, breast and ovarian cancer. We know that ovarian cancer is hard to detect. It's hard to treat. The treatment is often successful for a while but cancer often comes back and it's a cancer that has a high likelihood of causing fatality. So, what we recommend for women who are found to be at high genetic risk for ovarian cancer is that they remove their ovaries when they are finished with child bearing. Now that raises questions about early menopause and all those kinds of things, and in general, we do recommend that women who had their ovaries out early start taking estrogen therapy to prevent some of those consequences of early menopause.
So clearly, we can dramatically reduce the risk of getting ovarian cancer. For breast cancer, we can do very good screening. Some women choose to have prophylactic mastectomy to reduce the risk as much as possible. That's hard to prove that it saves lives, but by starting M.R.I. scans of the breast as well as mammograms at an early age, we can detect most cancer at an early stage before it really has a high chance of becoming life threatening. So you can actually do something about it if you are found to have one of these gene mutations that increase the risk for cancer.
Interviewer: What about lifestyle changes? Could that dramatically help to if I found that I have a gene mutation?
Dr. Buys: Well that's a really active area of research interest. We're doing studies here at Huntsman and other places, trying to figure out if you have got a genetic mutation, how much difference does lifestyle make? And it looks like it makes quite a lot of difference. So I don't think we can reduce the risk of getting breast cancer from 60% to 10% with lifestyle changes but we can have pretty dramatic influence.
For example, taking birth control pills really dramatically reduces the risk of getting ovarian cancer whether you've got a mutation, but importantly, if you do have a mutation, taking tamoxifen is less clear cut but it looks that taking tamoxifen, which is often used to treat breast cancer and is also used in general population in women who have a higher than average risk of getting cancer. So women who have mutation may be able to take medicines like tamoxifen and reduce that risk.
In addition, we know that child bearing practices, that exercise, that avoiding obesity, these things have a really powerful impact on the risk of getting cancer in the general population and also seem to have a benefit in individuals who are at higher than average risk. There is, again, a lot of interest in this and we here have done studies looking at means of reducing the risk of breast cancer in those with mutation and there are big studies, here looking at using medications to try to reduce the risk of getting colon cancer if you have got a strong family history of colon cancer, and particularly if you have a mutation that increases the risk of getting colon cancer.
Interviewer: Does a mutation mean I am going to get the cancer?
Dr. Buys: No, it doesn't. For most of the cancers, if you have the mutation, you have a much higher risk of getting the disease but it's not absolute. Some of the familial colon cancer syndromes, it's pretty close to 100%. If you have mutation in A.P.C., virtually 100% of people will get colon cancer. And if we know that, then we can take some steps to perhaps use medications in some of these trials, but probably more importantly, remove the colon before cancer develops. So it really depends on the specific gene mutation and the specific family syndrome, how likely it is that a mutation will make you get cancer.
Interviewer: If you think genetic testing might be relevant to you, where do you even start? You go to your family doctor or is there some place else?
Dr. Buys: Well, going to your family doctor is a good place to start because they may have some insight into who in your region is expert in doing genetic counseling and genetic testing. I mentioned genetic counseling because I think the genetic counseling piece is really important in the genetic testing. Many doctors feel comfortable ordering the test but a lot of the time they don't feel comfortable interpreting the result, unless it's really a clear cut, black or white.
Genetic counseling is also important because if you have a strong family history and no mutation is identified, there are still some important screening differences in your family compared to somebody else's family just because you do have a strong family history, whether or not there is a mutation identified.
Interviewer: So genetic counseling, where can I find that?
Dr. Buys: Genetic counseling, you could find by calling Huntsman Cancer Institute, calling the family cancer assessment clinic and you can give them information. And if it seems appropriate, they can answer question, they can get you set up with a genetic counselor.
Interviewer: What's the takeaway from this poll?
Dr. Buys: I think the major takeaway is that people still have a lot of misunderstanding about genetic testing and what it is, and some people who say they have had genetic testing probably haven't had genetic testing based on the cancers that they say they've had genetic testing for. So I think we still need a big information push. Genetic testing is in the news a ton and genetic testing is really important in some conditions and some families.
So I guess the takeaway from me would be, it's really important that people know their family history, and if you have a family history of diseases, particularly if they occurred at younger ages than normal and particularly if there are more people than you think ought to have that disease just by chance . . . and one general rule of thumb is, if you got three people in the family with a condition or related conditions and one has it at an early age, that's not something you might want to be thinking about talking to your family doctor about referral to a genetic professional.
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