Video
Utilization and Timing of Biomarker Tests for Prostate Cancer
Author(s):
Judd W. Moul, MD, FACS, provides insight into the timing of biomarker testing in the prostate cancer screening process, and discusses which patients might benefit the most from testing.
Patient Case: A 64-Year-Old Man with Elevated PSA Levels
- A 64-year-old-man underwent PSA testing during his annual physical with his primary care physician; PSA was 5.6 ng/mL and PSA density was 0.16.
- He then saw a urologist, who ordered a multiparametric MRI; result was PI-RADS 4.
- The patient was reluctant to undergo a prostate fusion biopsy, therefore the patient’s urologist recommended that he undergo exosome-based molecular testing to help determine risk of prostate cancer; his test score was 16.3.
- The patient and urologist remained concerned about his PI-RADS 4 MRI score. The urologist also noted that the PSA density of 0.16 was slightly above the threshold of 0.1.
- The patient elected to undergo TRUS-guided biopsy, which was negative for prostate cancer.
Judd W. Moul, MD, FACS: The question is how you use these tests, and in what sequence and in what order. It’s very controversial, and the truthful answer is it’s not crystal clear when and how. For example, say a gentleman has a baseline PSA [prostate-specific antigen] that’s abnormal. Depending on how high the PSA is, or also depending on what the findings for the digital rectal exam were, many cases would not necessarily need any other testing. One of the key teaching points is I never reflex any of these tests. In other words, I never just automatically order a biomarker test in situations like this. The MRI is a little different. Some people believe that the MRI should always be done before a prostate biopsy. If a patient has an elevated PSA and is going to go on to a biopsy, there are some experts who feel that the MRI should always be done as the next step before biopsy because the studies have suggested that the MRI adds value to help direct the needles.
On the other hand, let’s face it, an MRI is an expensive test, and MRI still has some quality assurance issues depending on where it’s done, and which radiologist is reading it, and how experienced the radiology group is in interpreting those MRIs. There is some subjectivity to it, and there is obviously a lot of cost. If you are of the mindset that you are always going to get an MRI, you are going to do that before you do any kind of other biopsy or biomarker. On the other hand, in my practice, I tend to place one of the biomarkers before the MRI. For example, our institution has the Prostate Health Index blood test done, easily available, that we do in house. That tends to be the most common secondary test that I do in my practice. I also am use the exosome urine test, and not as a reflex test, but as a way to fine-tune who actually may need an MRI or who may actually need a biopsy.
The issue is when do you pull the trigger for some of these secondary tests, especially in the PSA gray zone? And when we say the PSA gray zone, for many people that means PSA between 2.5 and 10 [ng/mL], or some people would use PSA of 4 to 10 [ng/mL]. Certainly, if a patient has a PSA in that gray zone, and if that patient has an abnormal digital rectal exam, then one can make an argument to go directly to biopsy without any sort of extra blood or urinary marker test. Similarly, if a patient has an MRI and shows a clear cut, for example, PI-RADS [Prostate Imaging Reporting and Data System] 5 lesion, then one could make an argument to go directly to a fusion biopsy without the need for any other biomarker testing.
However, some of these biomarker tests, such is the exosome tests, are really useful in patients who are in the gray zone, patients who have a PI-RADS 3 lesion, where it’s very difficult to know what to do. Or for patients who have a PSA between 2.5 and 10 [ng/mL] and a negative digital rectal exam and prostate enlargement, and especially patients who are reluctant to undergo prostate biopsy. I would say one of the biggest reasons I use some of these tests is the reluctance of patients to undergo a biopsy, and also sometimes even reluctance to undergo an MRI because of the cost. Or at some institutions the MRI involves an endorectal coil, meaning a probe placed into the rectum, and that can be invasive, and some patients don’t like that. There are clear indications to do these biomarker tests sometimes based on the data from PSA, but sometimes just based on the patient’s reluctance to undergo further testing.
Transcript edited for clarity.
