PARP Inhibitors in Prostate Cancer - Episode 1

Diagnosing Metastatic Prostate Cancer

Oliver Sartor, MD, describes the different tests routinely ordered for metastatic prostate cancer.

Matthew Fowler: Hello, and welcome to this contemporary CancerNetwork® OncView program titled “PARP Inhibitors in Prostate Cancer.” I’m Matthew Fowler, an editor with Cancer Network®. We have with us Dr Oliver Sartor, who is the medical director at Tulane Cancer Center and the Laborde professor for cancer research [at Tulane University School of Medicine in New Orleans, Louisiana]. Thank you for joining us. Let’s get started.

Oliver Sartor, MD: Thank you. Glad to be here.

Matthew Fowler: Dr Sartor, I’d like to start discussing diagnosis and testing. What testing do you routinely order for a patient with metastatic prostate cancer?

Oliver Sartor, MD: If the patient has metastatic disease, I already know that there’s been a scan or some evidence that confirms he’s metastatic. The first thing I like to do is conventional imaging; I get a bone scan, I get a CT scan, and I try to understand the extent of the lesions. That can get a little complicated if it’s what I call oligometastatic disease. Then I may want molecular imaging such as PSMA-PET [prostate-specific membrane antigen–positron emission tomography], which is newly FDA approved in the United States. That can get me a better delineation of small deposits that may not show on the CT scan and the bone scan.

I like to get the basic parameters on the labs: CBC [complete blood count], comprehensive metabolic panel, an LDH [lactate dehydrogenase]. I also get a baseline testosterone because I like to know what people’s testosterone is when they come in. Finally, of course I get a PSA [prostate-specific antigen]. In terms of molecular testing for those with metastatic disease, I always like to get a germline. Depending on the situation, I may want to get additional genetics as well. I can look at somatic genetics within the tumor, and I can also look at somatic genetics that are circulating tumor DNA. I can look at a transcriptome, but rarely would I do that in metastatic disease because that’s more of a risk classifier for those with localized disease. The bottom line is I try to get some scans and labs. Of course, I do a baseline assessment on the patient. Then for genetics, I always get a germline, sometimes somatic, depending on the circumstance.

Matthew Fowler: Could you expand on some of the types of biomarker testing you typically perform outside those you may have just mentioned? Such as NGS [next-generation sequencing], DNA, RNA?

Oliver Sartor, MD: Sure. Let me drill down a little more on the germline. First, let me say that germline testing is established in multiple guidelines. We know that’s important not only for the patient—it can serve as a predictive biomarker within certain genes—but also has very important implications for the family and some can test positive. I didn’t mention that I do cover family history when I begin the analysis of a patient. That’s not necessarily considered a biomarker, but it is a biomarker; that’s a way that can predict things that will happen.

On the somatic side, it’s often but not always that I’ll be getting what are called somatic next-generation sequencing analyses of the actual tumor. My predilection is to start simple, start with the biopsies I have in hand. I don’t necessarily chase any additional biopsies at the beginning. If you do that, a lot of the mutations we find are so-called truncal. They’ll remain from the beginning through the end of the patient. Things like the BRCA and BRCA2 mutations can often be picked up on primary prostate tissue. That’s 1 of the things that’s important to be able to identify, because of the treatment implications for BRCA and other genes that we can cover a bit later.

I mentioned that we don’t use a lot of transcriptomic analysis within the context of metastatic disease. That’s more of a risk classifier. I’m not endorsing anything, but like the Decipher test or the Prolaris test; those are patients who have early stage nonmetastatic disease, and we’re trying to do risk classification on them to make decisions about their local treatment or maybe their duration of hormonal treatment. That’s the way I frame it. I explain to patients that there could be an evolution of their tumor. There are some cases, particularly those with advanced disease, that I can pick up circulating tumor DNA. That can serve as an additional parameter that we can use to follow the patient, to serve as a biomarker. Tissue-based analysis, circulating tumor DNA, and germline analysis are the 3 components that I look at.

Transcript edited for clarity.