Physician Frequently Asked Questions

Understanding the ExoDx Prostate Test for risk assessment of High Grade Prostate Cancer

The ExoDx Prostate Test came back at “Higher Risk” but a biopsy result came back negative. How should I interpret this result?

The purpose of the EPI test is to rule out patients who don’t need a biopsy. If a patient is below the 15.6 cut-point, the chance of finding HGPCa is illustrated in Figure 1.  See bar chart. 

 

What is the Negative Predictive Value (NPV)?

Negative Predictive Value is a statistical measure that says how confident we are about a negative outcome. In the case of The EPI Test, an NPV of 91% means we are 91% certain that the patient will not have HGPCa at a cut point of 15.6 or less.

 

What is the sensitivity of The EPI Test?

The sensitivity of The EPI Test is 92%. The sensitivity measures the proportion of actual GS7 and above that are correctly identified as positive.

 

What is the cut-point used to determine high risk vs. lower risk?

The EPI Test has been validated using a cut point of 15.6 to determine when patients are at lower risk for high grade prostate cancer, defined as Gleason 7(3+4) or Grade Group 2 or higher. Patients with an EPI score below this cut point have a very low risk (9%) of not having high grade prostate cancer.

 

Does The EPI Test distinguish between GS6 and GS7 and higher prostate cancer?

Yes. The EPI Test is optimized as a rule out test to distinguish high grade prostate cancer (defined as GS7 and above) from low grade prostate cancer. Patients above the cut-point of 15.6 are associated with high risk of high grade prostate cancer. Patients below the cut-point of 15.6 are associated with lower risk of high grade prostate cancer. Reference  bar chart.  to see the likelihood of finding HGPCa in the intended use population.

 

Is the score a percentage of risk?

Recent data presented at ASCO GU 2019 Conference clearly demonstrated that the EPI score is proportional to increased risk of HGPCa. For example, an EPI score of 50 is associated with a 50% risk for HGPCa. See bar chart.  The risk should be considered within the context of other clinical factors in making a biopsy decision. A score of 60 or higher is not demonstrated to have higher risk than a score of 50.

 

Why do I need to use your collection cup?

The prostate biomarkers we are looking for have the highest concentration in the “First Catch” urine sample which is the first 20 mLs of the void and is mostly from the prostate. Using the ExoDx collection cup that we provide allows us to capture this first catch and discard additional urine that would dilute the sample.  Order a kit.

 

Which RNA biomarkers are analyzed?

PCA3, ERG and SPDEF

 

What should I do if the patient voided 30 minutes ago?

Please have the patient wait one full hour before providing a new sample. The ExoDx Prostate Test is most accurate when there is sufficient signal in the urine sample, which occurs with the First Catch.

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