Judd W. Moul, MD, FACS, introduces available blood- and urine-based biomarker tests for prostate cancer screening, and discusses how they might overcome limitations of commonly used modalities.
Patient Case: A 64-Year-Old Man with Elevated PSA Levels
Judd W. Moul, MD, FACS: Some of the tests that are done after a baseline PSA [prostate-specific antigen] would include blood tests and urine tests, and even maybe the MRI test could be considered a secondary test. In other words, the patient is at the primary care physician or their regular doctor and they get a baseline PSA. Then the next step used to be just moving directly to a prostate biopsy, and that is still appropriate in certain situations. But when we talk about these other secondary tests, that’s basically any test that you do between the baseline or initial screening PSA and the diagnostic needle biopsy. Blood tests that you could do include a Prostate Health Index, or PHI, which is a blood test that includes PSA but also includes some other derivatives that can help provide a more individualized risk assessment of prostate cancer. There is also a blood test called the 4Kscore, which is again similar to the Prostate Health Index, providing slightly more individualized risk assessment beyond total PSA.
There are 2 urines tests that could be ordered as secondary screening tests. In other words, you have abnormal PSA and you want to do something before you do a biopsy, or the patient wants to do something before the biopsy. The 2 urine options would be the ExosomeDx [ExoDx], which is a molecular urine test, or the other option is going to be the SelectMDx. I only have personal experience in my practice with the exosome test, and that test is most commonly at our practice done through mail order. When I want to order that test, rather than have the patient give the urine sample in the office, once we make the decision, my nurse orders it online, and then a kit is mailed to the patient’s home, so that he gives the urine test in the privacy of his own home and mails it back. That urine test does not require the performance of a rectal exam prior to giving the urine specimen. The only requirement is that the patient has to wait at least 1 hour before he gives the urine test. You could use first morning urine if you wanted to, but if the patient gives the urine specimen at a different point in the day, they have to wait at least 1 hour since their last urination before they give the urine for the exosome test. They urinate into a special collecting device that samples the initial urination, the initial phase of the urination is what is collected. That’s the exosome test, and that’s test that is based on expression of 3 genes that are measured from RNA that’s encased in these exosomes that are released into the urine.
The only thing that I would say about the SelectMDx urine test, which is the other test that’s available, again I have no personal experience with it, but that test requires an attentive digital rectal exam, or some people will call it a prostate massage, before the urine specimen is given. That one has to be done in the office after a rectal exam, and so that’s a little more clinically burdensome for the staff and also little more burdensome because the patient has to have a prostate massage before they have the urine test.
Transcript edited for clarity.