Somatic and Germline Testing for Prostate Cancer

Zachary Klaassen:

Hi, my name is Zach Klaassen. I'm a urologic oncologist at the Georgia Cancer Center in Augusta, Georgia. And I'm glad to be joined today by Dr. Sam Washington, a urologic oncologist at UCSF.

Somatic and germline testing for prostate cancer is a very complex topic, and this discussion with Dr. Sam Washington will be highlighting some of these topics and some of the health inequities associated with this testing. As I mentioned, very complex. For more information, we’ll provide additional details on prostatecancerpatientvoices.com.

So Sam, thanks for joining us to discuss this complex topic and really break it down for our patients who are listening to us.

Samuel Washington:

Happy to be here. It causes a lot of confusion with the terminology.

Zachary Klaassen:

I mean, jokingly, even my residents sometimes don't understand what all this is, so we really want to break it down for our patients. I think at a high level, what is somatic and what is germline testing when we're thinking about prostate cancer?

Samuel Washington:

And I think a lot of it is because we will just call everything genomic. We're looking at the DNA and signaling and pathways, but we really need to understand how much of that is inherited by family, how much is passed on from your parents, passed on to your children. And that's germline testing, germline genomic differences versus somatic. How much of that started in the prostate, for example, in the tumor and is due to changes over time, unrelated to what you got from family.

Zachary Klaassen:

Yeah. And just to break down a little further for the patients, I think germline, so they know it could be from blood, it could be from cells. It's any DNA in your body, tumor, somatic. And I think that's typically the way that I think about it as well.

Samuel Washington:

Yeah, that's the way I think of it as well too.

Zachary Klaassen:

Let's talk about why this is important for Black or African American men for prostate cancer. We know they're more likely to get prostate cancer, perhaps more aggressive prostate cancer. Why is germline and/or somatic important for them?

Samuel Washington:

It helps us understand a broader picture of risk. We know that Black men are higher risk of worse outcomes, more aggressive tumors. We also know if you have a family history, you may also be at higher risk. So understanding how those two overlap, is there some strong biologic risk factor that we need to know upfront to better tailor care for that patient is something that's very important.

Zachary Klaassen:

Yeah, absolutely. I think in general, when we look at testing, whether it be germline or somatic, there's need for uptake across the board, whether it be urologists or medical oncologists. We know specifically that Black men may be less likely to get it. So what are some of those barriers that may exist specifically for them getting this type of testing?

Samuel Washington:

In general, for any testing, providers comfortable to give the testing, patients comfortable asking about it, everyone being comfortable with conversations about it. And we know even from studies within the VA system, how you deliver that testing can dramatically change the receipt of testing by patients. So there's a lot of systems, clinic, and patient and provider level barriers. Always great to upfront ask if that's something that's provided or how you could get that test.

Zachary Klaassen:

Absolutely. I think it's important for our listeners to know that not everybody needs a separate testing. So maybe just outline who should be thinking about it, who should be asking about it, what patients.

Samuel Washington:

Yeah. And for this, I like to lean more on guidelines. So if we have men who are higher risk at baseline, if they're diagnosed with more aggressive, higher risk disease, testing could be important. If they're diagnosed and we're trying to better understand their risk, somatic testing may help us understand what treatments may be better for them longer term. So it really depends on which situation, but is always appropriate to ask, is there some form of germline or somatic testing that will help me?

Zachary Klaassen:

Yeah, absolutely. One term I think that may be confusing to patients is cascade testing. Maybe just talk about what that is in case they hear that term.

Samuel Washington:

Yeah. It's something where I almost think of it as a great opportunity to understand how other people get screened. So for example, if we have one person tested, one of my patients, I would ask, "Okay, how old are your children? Are your children or your parents also someone who'd be interested in testing?" In cascading from the one patient that we see in clinic to their family and others or friends helps us broaden the reach of testing to provide it to more patients.

Zachary Klaassen:

Yeah, absolutely. We could probably spend 30 minutes talking about the next question I'm going to ask you, but I'm going to ask it anyways, just maybe at a high level. When we get this testing, whether it be germline or maybe just focus on somatic testing, does that change how you're going to take the prostate out, how you're going to give radiation, how you're going to give therapy? How does that test, whether it be positive or negative, affect your treatment plan?

Samuel Washington:

I think a lot of times if we're thinking of prostate cancer, for example, multiple different treatment strategies that we have, depending on how aggressive a cancer looks. Somatic testing can give us insight to what that cancer looks like at a DNA level, molecular level, rather than just what it looks like on a slide from a biopsy. So it helps us fine tune the options. It's not going to dramatically change how I do surgery, for example. Some of that testing may fine tune what tests or medicines we use in more advanced disease.

Zachary Klaassen:

Right. And just getting it at the beginning, I think is important to know what that tumor looks like before we embark on the journey. I think as we wrap things up, I want to hit on being an advocate for yourself. So there may be a young African American gentleman listening to us or his family members listening to us. He's got high risk prostate cancer. What's the next steps? How does he go about talking about either germline and/or somatic testing with his team?

Samuel Washington:

Well, I think it's a good thing to start with places like Patient Voices, other online resources to understand what questions to ask. But understanding that a lot of our patients ask these same questions, I hope we can normalize the fact that asking these questions upfront are important and fairly common. So you're not burdening a provider or speaking out of turn, but you are advocating to get more information to help us better help you.

Zachary Klaassen:

Absolutely. My final point is precision medicine. We know that this is sort of a buzzword, not just in prostate cancer, but across all cancers, how we're targeting therapies. What does precision medicine for a Black man look like in prostate cancer, taking in access, taking in all this information? What would your message to them be?

Samuel Washington:

I think precision medicine has always been framed in terms of DNA, molecular testing. I think in terms of barriers to care, equity, we start to see that precision medicine can take on different terms. How do we optimize care delivery? How do we optimize access? A slightly different context for precision medicine. And I think there are a lot of questions we don't know yet, but I think us changing how we think about precision medicine and tailoring care is the overarching question we still have yet to answer.

Zachary Klaassen:

It's a great way to summarize our discussion. Sam, thanks as always for joining us on Prostate Cancer Patient Voices.

Samuel Washington:

Thanks for having me.