PCA3, mpMRI, targeted biopsies, and risk for diagnosis of prostate cancer

The degree to which the PCA3 test is a useful tool in assessment of risk for clinically significant prostate cancer prior to biopsy has never, really, been entirely clear. For example, there have long been relatively common findings of men with very high PCA3 values (> 100) who were found to have no sign of prostate cancer on biopsy.

A new paper by Fenstermaker et al. in the journal Urology (the Gold Journal) doesn’t explain why this may be the case, but it does at least shine a little more light on the problem.

The authors looked at data from nearly 200 patients, all being evaluated for risk of prostate cancer team by the highly experienced team at New York University’s Langone Medical Center between June 2012 and August 2014. These patients were all given both a multiparametric MRI (mpMRI) scan and a PCA3 test prior to being given an MRI/TRUS fusion-guided biopsy, and they had never received an earlier biopsy of any type.

Here are the core data reported by the authors:

  • The number of patients evaluated was 187.
  • A positive PCA3 result (based on a PCA3 cut-point value of ≥ 35)
    • Was associated with cancer risk among men with an MRI suspicion score of 2 or 3 (p = 0.004)
    • Was not associated with cancer risk among men with an MRI suspicion score of 4 or 5 (p = 0.340)

The authors conclude that:

Urinary PCA3 is associated with [the MRI suspicion score] and the detection of cancer on [MRI/TRUS fusion-guided biopsy] for men with no prior biopsies. PCA3 notably demonstrates a high negative predictive value among [men with an MRI suspicion score of] 2-3. However, in the case of high suspicion mpMRI, PCA3 is not associated with cancer detection on [MRI/TRUS fusion-guided biopsy] adding little to cancer diagnosis.

The clinical implications of this appear to be that there is little point in giving a PCA3 test to a man with a highly suspicious mpMRI score, and therefore that an mpMRI should always be given before any test sample is sent for a PCA3 test.

What is not evident from the abstract of this paper is the following:

  • Exactly how the authors were measuring what they refer to as the “MRI suspicion score” and how closely this might have correlated to the PI-RADS recommendations
  • Why the authors think there is less likely to be a correlation between PCA3 findings and mpMRI findings among men at higher risk based on the mpMRI findings
  • What percentages of the patients were found to have (a) no cancer; (b) very low risk for cancer on mpMRI (i.e., an MRI suspicion score of 1); (c) a low to moderate risk for cancer on MRI (i.e., an MRI suspicion score of 2-3); and (d) a high degree of risk for prostate cancer (with an MRI suspicion score of 4-5).
  • Whether the authors see any real clinical value for the PCA3 test by comparison with other possible tests today among previously unbiopsied men who are getting an mpMRI as part of their diagnostic work-up.

At least some (and possibly all) of this information is undoubtedly available in the full text of this paper, but we have only seen the abstract.

2 Responses

  1. The last sentence raises some interesting questions about just how the sitemaster examined the information.

  2. Oops. That last word in the last sentence should have said “abstract” as opposed to “biopsy”. Now corrected.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: