A new “gold standard” for detection of prostate cancer?

An article just published in the Journal of Urology argues that, ” The gold standard for cancer detection in primary biopsy is [now] a combination of systematic and targeted cores.”

The article, by a German research group (Radtke et al.), is based on data from a comparative analysis of data from a total of 294 consecutive patients suspected of having prostate cancer who received both a transperineal template saturation prostate biopsy and an MRI-targeted biopsy with MRI/TRUS-fusion guidance.

Since the full text of this article is available on line, individual readers may review this text themselves, but the basic facts are as follows:

  • The 294 consecutive patients were enrolled in 2013.
  • They were given
    • A 3 T multiparametric MRI (which was T2-weighted, diffusion-weighted, and dynamic contrast enhanced) without endorectal coil
    • A systematic transperineal biopsy with a median of 24 cores per patient, independent of MRI suspicion
    • An MRI/TRUS-guided, targeted biopsy with software registration that took a median of 4 cores per patient.
  • The highest Gleason score from each biopsy method was compared.
  • A total of 150 cancers were identified.
  • 86 of those cancers had a Gleason score ≥ 7.
  • Systematic, transperineal biopsy missed 18/86 tumors (20.9 percent) with  Gleason score ≥ 7.
  • MRI/TRUS-guided, targeted biopsy missed 11/86 tumors (12.8 percent) with Gleason score ≥ 7.
  • Targeted biopsy of PI-RADS 2 to 5 alone overlooked 43.8 percent of tumors with Gleason score 6.
  • Sampling efficiency favored of MRI-targeted prostate biopsy with
    • 46.0 percent of MRI-targeted biopsies detecting cancers with a Gleason score ≥ 7.
    • 7.5 percent of systematic, transperineal biopsy cores detecting cancers with a Gleason score ≥ 7.
  • To diagnose  a single cancer with a Gleason score ≥ 7 necessitated
    • 3.4 MRI-targeted biopsies
    • 7.4 systematic biopsies
  • Limiting biopsy to men with PI-RADS 3 to 5 would have missed 17 tumors (19.8 percent) with Gleason score ≥ 7.

While we would agree with the authors that their study again demonstrates that the best way to diagnose clinically significant prostate cancer with a high degree of certainty has been clearly proven to require a combination of systematic and MRI-targeted biopsies, we do have to point out that the current practicality of this approach is still very questionable — especially here in the USA where such a sophisticated biopsy process is going to be very costly and not very accessible for a very high percentage of men at risk because of the relatively small number of centers that has access to the relevant technology and the skilled uroradiologists capable of reading the MRI scans with accuracy.

In an editorial comment on this paper, Thomas et al. (also based in Germany) state that:

We agree that a combination of systematic biopsies and targeted biopsies seems to be the safest approach for [prostate cancer] detection.

They go on to note that:

However, combination biopsy is actually not ready for daily clinical practice. Results from large prospective studies with adequate power are needed to validate the cohort studies published to date. Moreover, a standardized protocol for such a biopsy approach is needed as a variety of imaging protocols and biopsy techniques exist.

A combination of systematic and targeted biopsy methods may well be the ideal that we seek to establish for the detection of prostate cancer. Making such methodology available to every patient will require patience and greater thought about who actually needs this type of biopsy. It would, for example, become more practical if we could cut down the number of men who are being given unnecessary biopsies every year.

One Response

  1. In our locale, reimbursement for the technical part of MRI/US, if reimbursable at all, is $100. An US/Fusion machine costs at least $250,000. Not economically feasible yet.

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