mpMRIs vs. biopsies for repeat evaluations on active surveillance


A question on the minds of many prostate cancer researchers and clinicians (not to mention their patients) is if and when we may be able to replace repeat systematic prostate biopsies for patients on active surveillance (or seeking to start on active surveillance) with the significantly less invasive multiparametric MRIs (mpMRIs). Based on data from a newly reported study from the prostate cancer group at Memorial Sloan-Kettering Cancer Center (MSKCC) in New York, the answer appears to be, “Not yet, anyway.”

Recabal et al. carried out a detailed and careful assessment of the data from > 200 consecutive patients — all with an initial Gleason score on biopsy of  3 + 3 = 6 — who were being evaluated for eligibility to enter the MSKCC active surveillance management cohort. The study goals were to determine: (a) whether mpMRI-targeted biopsies could replace systematic biopsies as a means to detect patients with a Gleason score of  ≥ 7, and (b) whether repeat biopsies could be avoided altogether based on mpMRI data among men with Gleason scores of 3 + 3 = 6 who were already on active surveillance.

Every man in the cohort who had a prior Gleason score of 3 + 3 = 6 on biopsy was initially given an mpMRI (not more than 3 months after their prior biopsy) and then another follow-up biopsy. The team at MSKCC used a standardized 5-point scale for estimating the clinical risk associated with the results from the mpMRIs. This scale is very similar to, but not exactly the same as, the PIRADs score.

Here are the core study findings:

  • The total number of men evaluated was 206.
  • 135/206 patients (65.5 percent) had an evident region of interest visible on mpMRI.
  • On re-biopsy, higher grade cancers (i.e., cancers with a Gleason score of 3 + 4 = 7 or higher) were evident in 72/206 patients (35.0 percent).
  • An mpMRI score of 3, 4, or 5 was associated with a significant probability (p < 0.0001) of detection of a higher-grade cancer as compared to an mpMRI score of 1 or 2.
  • mpMRI-targeted biopsies detected higher-grade cancers in 23 percent of all patents.
  • mpMRI-targeted biopsies missed higher-grade in
    • 17 percent of patients with an mpMRI score of 3
    • 12 percent of patients with an mpMRI score of 4
    • 10 percent of patients with an mpMRI score of 5

Recabal et al. conclude that, even though mpMRI-targeted biopsies do increase detection of higher-grade cancers for men on active surveillance than systematic biopsies alone,

a clinically relevant proportion of higher grade cancer was detected only using systematic biopsy.

They further conclude that

Despite the improved detection of disease progression using MRI-targeted biopsy, systematic biopsy cannot be excluded as part of surveillance for men with low risk prostate cancer.

What they do not discuss in this paper, however, is the frequency of either the repeat mpMRIs or the repeat biopsies. In other words, in a man who is actually on an active surveillance protocol after being confirmed to have Gleason 3 + 3 = 6 disease (and perhaps, in some cases, 3 + 4 = 7 disease) is a repeat mpMRI and a rebiopsy needed every year, every 2 years, every 3 years, or what?

The answer to that question, at present, may well depend on everything from the life expectancy and the specific characteristics of the individual patient to the skill and experience of the physician managing that patient.

One solution to this problem might be to give all patients seeking to go on to an active surveillance protocol a genomic analysis of his diagnostic biopsy material (using a test like a Prolaris or an Oncotype DX test) to see if that test can confirm whether he is a good candidate for active surveillance. Another solution might come with continued improvements in the quality of mpMRI scanning over the next 5 years or so.

 

5 Responses

  1. I would like to note a correction.

    According to the abstract, MRI-targeted biopsy alone missed higher grade cancers in 17%, 12% and 10% of patients with mpMRI scores of 3, 4, and 5, respectively.

    Instead of missed, the above summary reports incorrectly reports these as detected.

  2. Tom:

    You are correct and the error has been corrected above.

  3. To Sitemaster:

    Although my recent posts may have seemed somewhat critical, I would not want that to obscure how appreciative I am of the effort you and Allen make to produce this site. I have a leadership role in a support group, and this site is my primary means of keeping informed. The fact that I make a point to go back and read posts like this that I was too busy to read at the time is a testament to how vital this site is to me.

    A big big thank you to you and Allen, and any others whose efforts keep this site going!

  4. Dear Tom:

    Both Allen and I appreciate it when someone takes the time to point out our errors. We are only human, and there are only so many hours in the day!

    It’s good for us that there are people who keep an eye on us and try to “keep us honest”!

    :O)

  5. Errors? What’s taht? :-) Tom … actually, it helps me in the same way. Nothing helps me understand a study more than when I have to break it down and explain in clear, non-medical language. I constantly refer to this site to men in my support groups and in online forums. I am appreciative that the Sitemaster lets me do it.

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