Genetic Testing for Hereditary Breast and Ovarian Cancer, with Allison Kurian, MD, MSc

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Monika Sharda: Hi, I'm Monika Sharda, an editor at Cancer.Net, and your host for today's podcast. In this episode, we will discuss genetic testing for hereditary cancers. Our guest is Dr. Allison Kurian, a medical oncologist at Stanford University. She is also the Director of the Stanford Women's Cancer Genetics Clinic and serves as a Specialty Editor for Cancer.Net. Welcome, Dr. Kurian.

Dr. Kurian: Thank you so much for having me.

Monika Sharda: Dr. Kurian co-authored a recent study in the Journal of Clinical Oncology about genetic testing among breast cancer and ovarian cancer patients. Before we get into talking about the study, tell us about genetics and the role they play in cancer risk. What does it mean to have an inherited risk for cancer?

Dr. Kurian: Yes, that's a great question. And we've learned so much about it in recent decades really picking up the pace the last five years or so. What it typically means is that a person has inherited a genetic change from one of her parents. And I'm going to say “her” because it's mostly women we'll be talking about today, though it is the same in men when they inherit a change. And so she would have inherited a change in a gene that normally works to keep cancer cells from accumulating, to keep cancerous changes from growing in cells. And so when that happens, she often would be at higher risk than other people of ultimately developing a cancer. It doesn't mean that she definitely will, but it means that her risk is higher. Often two to five times higher.

Monika Sharda: So what does genetic testing for breast and ovarian cancers tell us?

Dr. Kurian: So what we do when we do genetic testing is it's generally first we would need to counsel a patient about her options and if she chooses to do genetic testing it would be a blood or a saliva test where we would sequence genes that are known to be implicated in maintaining a normal cell that doesn't turn into a cancer cell. And so we know from studies over the last few decades, that in patients who are born with an abnormality in one of these genes that their cancer rate is much higher than others. And so over the last 20 years, 25 years now, starting in 1994 and 1995 we've been testing primarily for two genes: BRCA 1 and BRCA 2. But over the last 5 to 6 years we've had the ability to test for many more genes and find many more patients who have an increased risk.

Monika Sharda: Based on existing guidelines who should receive genetic testing for these cancers?

Dr. Kurian: So that's a very timely question and I'll keep it simple, but I will just say that we're in the throes of a bit of a controversy in terms of what different guidelines are saying. I'm going to give you sort of the standard set of guidelines, which is to say that for breast cancer, it tends to be based on criteria like being diagnosed at a young age which usually means being diagnosed under age 50 or under age 45. It will be based on characteristics like having an unusual type of breast cancer: triple negative, or hormone-negative breast cancer is such a kind. Or having a strong family history, relatives with breast or ovarian cancer. That's the standard most would say for who should receive breast cancer testing. For ovarian cancer, it's actually a lot simpler. For more than a decade now guidelines have said if you have the most common type of ovarian cancer—which most people if they're going to get it, do get the serous kind—you should be tested, regardless of age, regardless of family history. So it's a pretty simple message with ovarian.

Monika Sharda: Thanks for providing us with that background on genetic testing. Now let's talk about your study. What were you hoping to learn from it?

Dr. Kurian: Yeah, so this study is the first time we've been able to look across a broad population. So prior studies have looked primarily in more restricted groups of people. So maybe people who were seen at one academic center or seen maybe in one health care system or perhaps getting testing from one laboratory. And so what we were able to do in this study, with the help of many wonderful collaborators, was actually to look at every breast cancer and every ovarian cancer patient diagnosed in the state of California and the state of Georgia. So leaving nobody out, which was really important, and looking at all the genetic testing results we could get on these people from the major labs that provide such testing and so we were really interested in what I would describe as a real-world view, taking everybody into account. What do we see in terms of who gets testing and what the results show?

Monika Sharda: Did you find that there are certain age groups or races and ethnicities that are less likely to get genetic testing for these cancers?

Dr. Kurian: We certainly did and interestingly enough, it was more pronounced with ovarian cancer than breast cancer. Now the reason I thought that was surprising is that I think for more than 10 years we've had pretty simple guidelines for ovarian cancer that pretty much say anybody who has it should get tested, right. That's not a very complicated guideline. And yet we found substantial under-testing of patients with ovarian cancer. Even though all of them are supposed to be tested, fewer than one-third of them were. That's a big gap. And we found significant racial differences, with African-American women significantly less likely to get tested than white women. And a problem also with insurance, so uninsured patients were much less likely to be tested and those were gaps that we really didn't see in quite the same way for breast cancer. But very pronounced for ovarian cancer.

Monika Sharda: And why do you think these gaps exist?

Dr. Kurian: So it's a great question. I think we don't know the answer yet. If I had to speculate on that, that's what we do when we think about this, I would say that it may be that ovarian cancer patients are older on average. We know that they often are than breast cancer patients. They, unfortunately, often are sicker at diagnosis because they tend to be diagnosed at a later stage. It may be that those things are barriers to getting sort of an additional part of their care, that being genetic testing. I think it's a bit puzzling why the insurance should be such a problem because it actually traditionally has been easier to get testing covered for ovarian cancer than breast cancer again because the guidelines are simpler, but certainly for people who are underinsured or have insurance that does not work so well for them or minimal insurance, the costs certainly can be an issue even though costs have come down. So I think there are a lot of questions as to why it should be more ovarian than breast, but it's clearly a big problem.

Monika Sharda: Are there other key takeaways from your study that we haven't already discussed?

Dr. Kurian: There are, so I think a few different things. One thing that some may have considered surprising is that actually a fair amount of breast cancer patients in these states got tested. It was a quarter of patients. Some might consider that a high number because we haven't had guidelines that said the majority of breast cancer patients should be tested. That may be changing. But so I think some may say the word has gotten out reasonably well at least for genetic testing of patients with risk factors for breast cancer. And I think some other interesting facts here were the prevalence of how common genetic mutations are. We found that 8% of people tested who had breast cancer did have an important genetic finding, 15% of those with ovarian cancer. And those are significant numbers. Numbers that I think do confirm the importance of doing this. And I think those are key takeaway points.

Monika Sharda: And how can these findings from your study help us? You started to talk about this a little bit already, but what can we do to overcome these disparities that you've just mentioned?

Dr. Kurian: I think it's an excellent and really important question, and I would say like so many things sometimes shining a light on what is actually there can be powerful. So I think a study like this that looks at 77,000 patients with breast cancer and 6,000 patients with ovarian cancer, it's really a huge number, has a lot of power to show us as doctors and as patients and as a society what's actually happening. I think these numbers may be surprising to people, to see how low they are for ovarian cancer. And I think things like that tend to be motivating for those of us who have a role in this, namely oncologists and other clinicians, to redouble our efforts to get the word out in terms of ovarian cancer testing, in terms of making sure that we offer education to our patients, and we do everything possible to make it easier for our patients, particularly those with ovarian cancer or those who may be more likely to have an underserved situation either in terms of insurance or racial-ethnic discrimination or other challenges. So I think that's part of it, but I think certainly work needs to be done further to understand exactly why these gaps exist. So I've been speculating, but I think more work needs to be done really to gather data on why this is happening so that we can do something to intervene.

Monika Sharda: And is there a takeaway for patients here as well? Do you think there's something that they can be doing? You mentioned how oncologists can be more involved and aware of these disparities, but is there something that patients can be doing as well?

Dr. Kurian: Absolutely. I think certainly for anyone with ovarian cancer, ask your doctor about genetic testing. Because it really is important and it can help in terms of your treatment. And it also can help in terms of your relatives. And it's a really important thing to do. So that would be my main comment there and I think certainly breast cancer patients as well, asking your doctor about these options is an important thing to do.

Monika Sharda: Thank you for joining us today, Dr. Kurian. You've very comprehensively explained how genetic testing works, who should consider genetic testing for breast cancer and ovarian cancer and you've highlighted the key takeaways from your study. This is all really useful information for our listeners. And before I let you go can you share some resources where people can learn more about this topic?

Dr. Kurian: Absolutely. I always think Cancer.Net is a wonderful resource. I think some other great resources for genetic testing and things that patients, I think, can understand well. One of them is a group called Facing Our Risk of Cancer Empowered or FORCE. I think that can be a very good one for hereditary risk of breast and gynecologic cancers.

Monika Sharda: Thanks again, Dr. Kurian.

Dr. Kurian: Thank you so much. Really appreciate it.

ASCO: Learn more about the genetics of cancer and hereditary cancer risk at www.cancer.net/genetics. And if this podcast was useful, please take a minute to subscribe, rate, and review the show on Apple Podcasts or Google Play.

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