Germline Testing in Patients with Breast...

Dr. Isabelle Bedrosian and Dr. Mark Robson discuss the new guideline from ASCO and SSO on germline testing in patients with breast cancer. They discuss the framework for which patients should be offered BRCA1/2 testing, and what additional moderate- and high-penetrance genes may be considered for inclusion in germline testing. They highlight key aspects of personal and family history, recommendations surrounding counseling for genetic testing, and the impact for patients and their families. They close the conversation with a discussion of gaps in the research.
Read the full guideline, Germline Testing in Patients with Breast Cancer: ASCO-SSO Guideline

TRANSCRIPT

This guideline, clinical tools, and resources are available at http://www.asco.org/breast-cancer-guidelines. Read the full text of the guideline and review authors' disclosures of potential conflicts of interest disclosures in the Journal of Clinical Oncology, https://ascopubs.org/doi/10.1200/JCO.23.02225

Brittany Harvey: Hello and welcome to the ASCO Guidelines Podcast, one of ASCO's podcasts, delivering timely information to keep you up to date on the latest changes, challenges, and advances in oncology. You can find all the shows, including this one, at asco.org/podcasts. 

My name is Brittany Harvey, and today I'm interviewing Dr. Isabelle Bedrosian from the University of Texas MD Anderson and Dr. Mark Robson from Memorial Sloan Kettering Cancer Center, co-chairs on "Germline Testing in Patients with Breast Cancer: American Society of Clinical Oncology – Society of Surgical Oncology Guideline." 

Thank you for being here, Dr. Bedrosian and Dr. Robson.

Dr. Mark Robson: My pleasure.

Dr. Isabelle Bedrosian: Thank you, Brittany.

Brittany Harvey: Then, before we discuss this guideline, I'd like to note that ASCO takes great care in the development of its guidelines and ensuring that the ASCO conflict of interest policy is followed for each guideline. The disclosures of potential conflicts of interest for the guideline panel, including Dr. Bedrosian and Dr. Robson, who have joined us here today, are available online with the publication of the guideline in the Journal of Clinical Oncology, which is linked in the show notes. 

So then, to jump into the content of this particular guideline, Dr. Bedrosian, could you give us a general overview of both the scope and the purpose of this guideline?

Dr. Isabelle Bedrosian: Yeah, sure. So, in the last decade or so, the whole area of clinical cancer genetics has become incredibly complicated, driven, I think, predominantly by the development of extended gene testing. And in the midst of this complexity, our goal here was to try to give providers a framework through which they can think about the application of germline testing within their patient population. And really, this framework was to help them think through how testing can best be applied to patients that were both newly diagnosed with breast cancer or had a history of breast cancer, and also to help them think through the scope of that testing as well, be it BRCA testing or testing in a more extended fashion that may help inform longer-term decisions such as risk management.

Brittany Harvey: Absolutely. We appreciate your efforts to provide recommendations in this framework in this complicated space. 

So then, I'd like to review the key recommendations of this guideline developed by the expert panel. So first, Dr. Robson, who should be offered BRCA1/2 testing?

Dr. Mark Robson: Thank you. I think this is perhaps one of the most important things that comes out of the guideline is that we, and the group, are now recommending that anyone who is either newly diagnosed with breast cancer at or before the age of 65, or if they're over 65 and have suggestive personal or family history criteria, or alternatively, if they are eligible for PARP inhibitor therapy, that they all be offered BRCA1 or BRCA2 testing. And the same would hold for women who had a personal history of breast cancer but were not currently under active treatment if their diagnosis had been made at or before 65 or older than that, with certain criteria then they should be offered testing. This is a much simpler way to look at things than the rather complicated existing criteria, which are perhaps a bit both difficult to remember and unfortunately inadequately sensitive in a setting where there is such critical, both therapeutic and risk management implications to the identification of a BRCA mutation.

Dr. Isabelle Bedrosian: Yeah, I would just also add there's one other, albeit a much smaller group of women for whom BRCA testing could be considered, and those are women who develop a second primary breast cancer. That's another group that I think we can think about offering BRCA1/2 testing to.

Brittany Harvey: Understood. I appreciate you both reviewing those recommendations for BRCA1/2 testing. 

So, Dr. Bedrosian, which additional genes does the panel recommend including in germline testing?

Dr. Isabelle Bedrosian: Yeah. So, in this area, outside of BRCA genes, Brittany, I think the panel didn't make any definitive recommendations or any specific genes that should be tested for. I think the panel felt that the decision to test for additional high penetrance genes and also for some moderate penetrance genes should be guided by the specifics of the individual case, whether the identification of germline mutations makes sense in the context of the patient's personal history and family history. So, in other words, is there a worrisome pattern in the family that might warrant more in-depth testing beyond BRCA, and also considerations around the implications of those test results. Would it change the management for the patient themselves? Either in the treatment of the index malignancy, which, in the case of most of these non-BRCA genes, there really is not changes to the management of the breast cancer that would be offered based on the finding of non-BRCA germline mutations. But potentially, the finding of a non-BRCA germline mutation in a breast cancer patient might help better understand risks of second malignancies that would then be addressed. And certainly for families as well of the patients, identifying those that are carriers could offer opportunities for risk assessment, risk mitigation.

Dr. Mark Robson: I totally agree with Dr. Bedrosian. One thing I think it's important to understand is that most commercial testing done in the United States now does involve panels of genes. And the group certainly did not intend to suggest that that practice not continue. So, I think if somebody has a history of breast cancer, I think the panel felt that it would at least be reasonable to test for breast cancer susceptibility genes. However, this issue of do you test for all of the high penetrance genes when the family history doesn't suggest it, was certainly something we left open and we did not want to imply that it was obligatory to test for a large number or large panel of genes that weren't related to the patient's personal and family history. So, in other words, didn't want to imply that it was obligatory to do an extremely large panel just as a target of opportunity, if you will.

Dr. Isabelle Bedrosian: I think really a key part of these guidelines was that we wanted to afford the oncologist flexibility. It's very difficult beyond BRCA to be prescriptive. There are so many considerations about testing, and those considerations will be applied differently in every patient context. So, we really wanted to let providers know that while they have to think about these other genes, and oftentimes there'll be good reason to do these other genes as part of the overall germline testing, again, that it's not obligatory to do so. It's not a fixed set that needs to be tested for. And really, the understanding of the patient's personal history, family history, therapeutic goals, and risk assessment goals should be used to determine kind of the ultimate scope of the testing.

Brittany Harvey: It sounds like these decisions will be individualized, based on patient characteristics and with working between both patients and their clinicians. So that leads into my next question. But, Dr. Robson, how should patients with breast cancer considering genetic testing be counseled?

Dr. Mark Robson: With this recognition and emphasis on the therapeutic implications for patients with breast cancer, both surgical and potentially systemic using PARP inhibitors, the approach has gradually moved away from the concept of testing for personal utility, in other words, just wanting to know, and more towards the idea of this being a clinically useful test that's to some extent necessary for the appropriate management of a fair number of patients. And so the counseling is usually- the pre-test counseling is perhaps more educational than we have used in the past, rather than this extensive discussion of whether or not somebody wants to know. Obviously, it's always the patient's ultimate decision whether or not to be tested, and we have to give them the same elements of education that we would have given back in the day. But it can be delivered in a more didactic type of context rather than necessarily the back and forth that takes place with formal genetic counseling. 

Now, for patients who have complicated or extensive family histories or who have histories that may suggest predispositions other than those for breast cancer, the type of thing that Dr. Bedrosian was talking about earlier, they could certainly benefit, again, from a more formal evaluation by a provider experienced in cancer genetics to help select what the scope of the testing should be, for instance, and also to help interpret those results. And certainly anybody who had a pathogenic variant or a likely pathogenic variant identified should be considered for meeting with somebody who's experienced in clinical cancer genetics both to interpret and also to help with family expansion when appropriate. 

Brittany Harvey: Excellent. Thank you for reviewing those recommendations from the expert panel. So, Dr. Robson just touched on this a little bit, but Dr. Bedrosian, how will these guideline recommendations affect patients with breast cancer and their families?

Dr. Isabelle Bedrosian: Yeah, so from a patient perspective, I think there are two ways that these recommendations can impact care. For those women that are identified as germline carriers, specifically with BRCA, it will open the door for receipt of PARP inhibitors, which are currently recommended for patients that are high-risk primary cancer or those with metastatic disease. The other ways that patients will be affected by a germline testing is really in this idea of second cancer risks. Some of these germline mutations are well established to carry risks of either second primary breast cancer or non-breast malignancies. And understanding those risks will allow the patients and their providers to create management strategies, be they surgical or with more intensified screening that will help them mitigate the effects of that germline-driven risk. 

And I think similarly for the families of patients, the ones the proband has identified, I think that family now has a very real opportunity to better understand their cancer risks and again be able to more effectively manage those risks through either surgical or non-surgical means. And it would really underscore the family component of this. I think oftentimes oncologists are very much focused on the patient and admittedly so that is the person that has the most immediate needs. But I think there's a real opportunity to extend efforts at prevention and early detection by identifying the at-risk family members and allowing them the opportunity to access care that mitigates their cancer risks and hopefully will improve survival outcomes in so doing. So, I think the opportunities for families here to understand risks of germline testing is a really important one to underscore from these recommendations.

Dr. Mark Robson: Just to expand a little bit on what Dr. Bedrosian was saying, I think this is a very important place for collaboration between the oncology community and the clinical cancer genetics providers because the oncologist is pretty occupied taking care of all of their cancer patients, and the approach to people who are unaffected is a little bit different. People who are unaffected perhaps do need a little bit more pretest counseling to understand the pros and cons of choosing to be tested for the familial mutation. And certainly that idea of family expansion is something that's well known to clinical cancer genetics providers and that's really very much something that they can help the primary oncologists do.

Brittany Harvey: Absolutely, these recommendations have impacts beyond just the individual patient, but also for their families as well. 

So then, finally, Dr. Robson, what are the outstanding questions regarding germline testing in breast cancer?

Dr. Mark Robson: Oh, there are so many. Where should I start? I think over the years we've become, as a community, pretty comfortable managing individuals who have BRCA1 or BRCA2 mutations. There are certainly some questions left, but there's a lot of familiarity with that. I think the challenges expand into these what we call moderate penetrance genes and how to guide people with alterations in those genes. Because except for PALB2, which is relatively uncommon, many of the other genes don't really have the same implications for therapy because it's not clear that they confer PARP sensitivity. It's not at all clear that they have high risks of contralateral breast cancer. And even in the unaffected setting, we know that there's a wide distribution of risk for people who carry these alterations. And some individuals with these alterations probably are not at increased risk at all because they have protective factors. So the management of breast cancer susceptibility genes beyond BRCA1 and BRCA2 is still very much in evolution. They can't be handled exactly the same way as a woman with a BRCA carrier.  

And then, of course, this issue of how much should we test and what do we do with some of the alterations that we find, if you will, out of context, what are the implications for that and what's the most appropriate management? Those still remain very much open questions. So I think there's still plenty of work to do.

Dr. Isabelle Bedrosian: Yeah, I agree. I think one of the enormous challenges has been the disconnect between how rapidly our technology has advanced and can sequence alterations, and our ability to really understand the biologic and clinical implications, which really is a time-dependent issue. We need to see over time how patients do for us to understand the implications of some of these germline findings. So that disconnect is a very difficult one to bridge, particularly, I think, for surgical oncologists because they are oftentimes referred patients who don't have a cancer history, necessarily, or have a distant history, and really the concern is "I'm at risk and I would like to reduce my risk." And it becomes very difficult to counsel patients as to the benefits of risk reduction when we don't have such a great handle on the degree to which they are actually at risk. So that really is a significant gap, I think, for surgeons in particular to have to contend with.

Brittany Harvey: Definitely. We'll look forward to answering some of those questions as we learn more and get more data to address those gaps.

 So I want to thank you both so much for your work to develop this framework for genetic testing in breast cancer, and thank you so much for your time today, Dr. Robson and Dr. Bedrosian.

Dr. Isabelle Bedrosian: Thank you, Brittany. 

Dr. Mark Robson: Thank you for having us.

Brittany Harvey: Thank you to all of our listeners for tuning in to the ASCO Guidelines Podcast. To read the full guideline, go to www.asco.org/breast-cancer-guidelines. You can also find many of our guidelines and interactive resources in the free ASCO Guidelines app, available in the Apple App Store or the Google Play Store. If you have enjoyed what you've heard today, please rate and review the podcast and be sure to subscribe so you never miss an episode.

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