The potential of focal therapy: another assessment

For several years, various research teams have been assessing the potential of focal therapy as a means to treat carefully selected men with localized prostate cancer. However, to date, the ability to identify such men with accuracy prior to such treatment is still in question.

In theory at least, focal therapy offers the opportunity to eliminate cancer in a man’s prostate while minimizing risk for complications such as urinary incontinence and sexual dysfunction. However, prostate cancer is commonly found (after whole gland radical postatectomy) to be a multifocal as opposed to a unifocal disease, even in men who have been given saturation biopsies with only one positive biopsy core.

Katz et al. have carried out a restrospective analysis of data from a series of 599 patients who were given a transrectal ultrasound (TRUS)-guided prostate biopsy followed by radical prostatectomy for localized prostate cancer between 2001 and 2009. They state that they “established very restricted criteria to select patients with very-low-risk disease for whom focal therapy would be suitable (only 1 biopsy core positive, tumor no larger than 80% of a single core, no perineural invasion, PSA serum level < 10 ng/ml, Gleason score < 7 and clinical stage T1c, T2a-b).”

In other words,they divided their 599 patients into two groups based on the pre-surgical biopsy and related data: those who would have been theoretically appropriate for focal therapy based on the criteria above and those who would not. They then used the post-surgical pathology data to assess whether, in fact, the men who were theoretically appropriate for focal therapy would have received effective curative treatment if focal therapy had been given.

Here are their findings:

  • Only 56/599 men (9.3 percent) met the pre-surgical criteria for focal therapy.
    • The average (mean) age of these men was 59 years.
    • The mean number of biopsy cores taken from these men was 14.4.
    • 47/56 (83.9 percent) were clinical stage T1c.
    • 9/56 (16.1 percent) were clinical stage T2a-b.
  • 44/56 patients  (78.6 percent) would apparently have been adequately treated by focal therapy.
  • 12/56 patients (21.4% percent) would clearly not have been adequately treated by focal therapy.
    • All 12 patients had a bilateral, significant secondary tumor.
    • 7/12 men (58.3 percent) had a Gleason score ≥ 7.
    • 3/12 men (25 percent) were pathologic stage pT3.

Based on this series of 56/599 men, it is evident (yet again) that we do not yet have the tools to accurately identify men who are truly eligible candidates for focal therapy, unless we are willing to carry out extensive imaging and saturation biopsy studies prior to surgery — and even then it is known that some men will still be found to have had multifocal disease that was no evident at the time of initial treatment.

In saying this, we are by no means suggesting that the potential of focal therapy should no longer be explored. We are, however, suggesting that any patient who wants to consider focal therapy should be having it carried out within the context of a well-defined clinical trial conducted by an appropriately experienced research team. That way the patient will likely be getting high quality care (despite the risks) and everyone else in the future will have the opportunity to benefit from the data collected and the skill sets that are being enhanced.

5 Responses

  1. You are right, the imaging is the key. The 3D mapping biopsy is available along with MRI procedures that will give a clear picture as to the extent of the cancer so that the treatment can be focal.

    It is true that targeted focal therapy is not for everyone, but with these latest imaging techniques up to 40% of men with prostate can would qualify for the procedure and thus enjoy an improved quality of life post-operatively.

    I had both a 3D mapping biopsy which discovered my cancer and targeted focal therapy. My cancer was small; 10% one core Gleason 6. It just made sense to treat that one spot and preserve my quality of life.

    It was done at a university center and I believe I am making the contribution you speak about.

  2. The percentage of men with likely success, within the eligible group, is impressive! It’s also interesting that the vast majority of men in the series were not considered eligibe for focal therapy (about 91% ineligible). While it would be disappointing to learn your case was not eligible for focal therapy, it would also be reassuring in a sense to know that you had not missed out on an approach that likely would have substantially reduced side effects.

    It’s also noteworthy that a median of 14 biopsy cores were taken using standard ultrasound technique. In contrast, leading focal cryotherapy experts are using either 3D-mapping saturation biopsies (Dr. Gary Onik), featuring many more cores sampled, or color Doppler ultrasound (Dr. Duke Bahn). There’s no way of knowing at this point, but one can’t help but wonder whether either of these techniques would have smoked out a large proportion of the 21.4% of cases that would not have benefited.

    I suppose, if funding were available, it might be possible to backfit the Katz biopsy protocol onto the Onik and Bahn data, which could give useful points of comparison with the Katz results. For example, the Katz protocol determined number of cores to be sampled for a patient could be used to blindly select cores in the Onik saturation biopsy cores for tallying. Of course, with cryo, the option exists to go back for a second full treatment if there is a recurrence after a focal treatment.

  3. But James … My questions — with the numbers you provide — would be whether you needed immediate treatment at all (based on available active surveillance data)? That’s hard to tell since you don’t give either your age or your life expectancy.

  4. But James … My questions — with the numbers you provide — would be whether you needed immediate treatment at all (based on available active surveillance data)? That’s hard to tell since you don’t give either your age or your life expectancy.

  5. Jim: You have completely lost me.

    Katz et al. didn’t have a “protocol” for determining the “number of cores to be sampled” for patient having focal therapy. The number of biopsy cores they refer to is simply the number of biopsy cores that was available based on patients who went on to have a standard RP at their institution.

    What you also seem to be overlooking here is that to find the 56 men who were potentially eligible for focal therapy up front (with any reasonable degree of accuracy) one would have had to do mapping biopsies and 3-T MRIs on 599 patients. The cost would be outrageous. Remember that almost none of these 599 men is at any significant risk for prostate cancer mortality since they have low-risk disease. Arguably, up to 40% ofg these men should simply have gone onto active surveillance.

    Just because something can be done doesn’t necessarily make it right to do it. Are you willing to pay out of your pocket for all those 599 men to have a 3-T MRI and a mapping biopsy — at a ballpark cost of around $6 million — to better identify the “good candidates” for focal therapy that 25 to 40% of them probably don’t even need?

    Before we are able to even consider a strategy like this, we need a much better and a much more cost-efficient way to identify appropriate candidates for focal therapy.

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