Results of repeat biopsies under electronically tracked, MRI/TRUS fusion guidance


Dr. Leonard Marks and colleagues at the University of California, Los Angeles were among the earliest groups to start to use and publish data on MRI/TRUS fusion biopsies of the prostate. They have now reported some early data on repeat biopsies using such methodology in men on active surveillance.

The paper by Sonn et al. in Urologic Oncology provides data on initial and repeat biopsies, under MRI/TRUS fusion guidance, of patients who were all given an initial biopsy and a repeat biopsy between March 2010 and January 2013. The men’s initial biopsies all included 12 cores based on a standard template (which were mapped using proprietary software) and directed biopsies from regions of interest seen on an MRI. In the repeat biopsies, samples were taken exclusively from sites known to have been cancerous on the initial biopsy. The researchers applied an electronic tracking system (the Artemis technology) to track the original biopsy data and to plan the repeat MRI/TRUS fusion-guided biopsies.

Here are the core findings of the study:

  • 53 men underwent an initial MRI/TRUS fusion-guided biopsy and were found to have prostate cancer with clinical stage T1c.
  • These 53 men had a total of 74 positive biopsy cores on initial biopsy.
    • 63/74 cores (85 percent) were Gleason 3 + 3 = 6.
    • 11/74 cores (15 percent) were Gleason 3 + 4 = 7.
    • 51/74 cores (69 percent) were found on systematic 12-core biopsy data.
    • 23/74 cores (31 percent) were found within an MRI-targeted area.
  • On repeat MRI/TRUS fusion biopsy
    • 29/74 positive cores (39 percent) were again detected.
    • There was no correlation between Gleason score of the original core and re-detection on the repeat biopsy.
    • Re-detection on repeat biopsy was directly related to the length of the cancerous region of the original biopsy core (P < 0.02).
    • 9 of the re-biopsied sites showed an increase in Gleason score
  • Of the cancerous regions identified on repeat MRI/TRUS fusion biopsy
    • 61 percent were in regions found in the MRI targeted areas found to be positive on initial biopsy.
    • 29 percent were in regions found on the initial 12-core, systematic biopsy.
  • When a patient’s initial cancer core length was ≥ 4 mm and had been identified by MRI targeting, 5/6 follow-up biopsies (83 percent) were positive.

Sonn et al. conclude that:

Monitoring of specific prostate cancer-containing sites may be achieved in some men using an electronic tracking system. The chances of finding tumor on repeat specific-site sampling was directly related to the length of tumor in the initial biopsy core and presence of tumor within an MRI target; upgrading of Gleason score was uncommon.

It has to be said, however, that these conclusions are based on data from a very small number of patients, and that the re-identification of only 29/74 positive cores found on the original biopsy is a little worrisome.

The authors claim that only 9/74 original biopsy cores (12 percent) showed an increase in Gleason score, which would be very promising if we knew that it was absolutely true. Another way to look at these data would be to say that 9/29 positive biopsy cores re-identified on re-biopsy (31 percent) showed an increase in Gleason score and that the technique used failed to re-identify the presence of cancer in 45/74 regions of the prostate that were originally cancerous. It is certainly possible that 45/74 of the cancers found in the original biopsies went into spontaneous remission, but this does seem to be a little on the unlikely side. The question that is therefore raised by these data is, just how good is the electronic tracking system and related software in assuring a precise re-biopsy of the region that was originally found to be biopsy-psoitive?

It is hard to know exactly what to make of these data reported by Sonn et al. It is certainly true that, as they are also careful to note in their conclusions:

Further research is required to evaluate the potential utility of site-specific biopsy tracking for patients with prostate cancer on active surveillance.

 

6 Responses

  1. Is this study applicable to “in bore” MRI, where the lesions are visualized in “real-time’ for each biopsy?

    It looks to me like it is pertaining to MRI/US fusion.

    Thanks

  2. Doug:

    No. I don’t think so. As far as I can tell it relates only to MRI/TRUS fusion, as we stated above. “In bore” MRI-guided biopsy is a much more complex process that is very expensive (as I understand it). Whether “in bore” MRI-guided biopsies can be repeated with high levels of accuracy is also unknown at this time.

  3. My second MRI fused biopsy only showed one of the three previously identified positive spots (done at University of Southern California). All the positive samples were all less than 20% of the cores. This makes me wonder about the [accuracy of the] ability of sampling the same spots even with the sophisticated software. All of my initial positive samples were all Gleason 6. No change to the Gleason score the second time.

  4. Also; were the MRI sites a second positive core for each of the 53, or the only indication of cancer in some?

    Fewer (23) MRI sites than standard core (53) initially, yet only 15 of the 53 (29%) were cancerous on repeat? Biopsy cures cancer is the logical conclusion. (Not my belief.) Certainly raises the question of what is Gleason 6.

    Rather a baffling report.

  5. Mike H:

    As I understand the report, there were 51 cores that were identified by the 12-core biopsies at the initial biopsy and another 23 cores that were identified exclusively by MRI targeting. The abstract does not tell us how many of the 51 cores identified by the 12-core biopsies were also visible on MRI (although I would expect this information to be available in the full text of the paper if someone wants to go looking).

  6. There are several aspects to the study in question.

    First the study started in 2010 and ended in January 2013. From my direct experience becoming involved in clinical trials in January 2013 concerning MRI, MRI-guided biopsies and MRI-guided focal laser ablation (FLA) at the National Institutes of Health, this type of biopsy was done to follow my 2009 FLA.

    The state of the art has changed over time — as one would expect it to do so when one of the most respected cancer research centers in the world is working to refine the MRI process. The first MRI scan I had in January 2013 had no resemblance to the MRI scan I had in January 2014. Hardware, software, contrast agents, use or non-use of coils, almost everything to do with newer forms of MRI scanning has evolved. The use of early generation 3 T mpMRI data would not be representative of the current state-of-the-art MRIs. The research community is committed to making MRI technology for prostate cancer a foundation for detection and monitoring. The University of Minnesota began testing 7 T MRIs for use in the prostate field last year. The University of Iowa took delivery of their 7 T MRI in June. The days of blind biopsies and inaccurate PSA tests which have lead to massive over-treatment of prostate cancer, with dire consequences, are coming to an end.

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