Feasibility of focal HIFU: a pilot study with 10-year follow-up data

The potential of high-intensity focused ultrasound (HIFU) as a form of focal therapy for treatment of cancer isolated to a portion of the prostate as opposed to treatment of the entire prostate has been recognized for a considerable period of time. However, limited data are available so far on the outcomes of men treated with focal HIFU.

El Fegoun et al. have recently reported data from a small, pilot study designed to evaluate the long-term efficacy and complications of focal HIFU in the first-line treatment of localized prostate cancer in a series of relatively elderly men between June 1997 and March 2000.

To be eligible for inclusion in this study, the patients had to meet the following criteria:

  • PSA level ≤ 10 ng/ml
  • ≤ 3 positive biopsy cores, all limited to only one lobe of the prostate
  • Clinical stage ≤ T2a
  • Gleason score ≤ 3 + 4 = 7
  • Negative CT scan and bone scan

All patients were treated by hemi-ablation of the prostate (application of HIFU to only the lobe of the prostate that was biopsy positive) using the Ablatherm device. Control biopsies were performed at 1 year post-treatment. Treatment failure was defined as a positive biopsy post-treatment or the need for subsequent salvage therapy.

Here are the key results of this pilot study:

  • The trial included just 12 patients treated over a 21-month period.
  • The average (mean) age of the patients was 70 years.
  • The average (median) follow-up was 10 years.
  • Control prostate biopsies were negative in 11/12 patients (91 percent).
  • Overall survival was 83 percent (10/12 patients).
  • Prostate cancerspecific survival was 100 percent at 10 years.
  • 2/12 patients (17 percent) died from non-prostate cancer-related causes.
  • Recurrence-free survival was 90 percent at 5 years, but only 38 percent at 10 years.
  • 5 patients needed salvage therapy with either repeat HIFU (n = 1) or hormonal therapy (n = 4).
  • All patients who needed salvage therapy were alive at 10 years.
  • No patients developed lymph node or bone metastasis.
  • No patients suffered from urinary incontinence.
  • Patient’s International Prostate Symptom Scores (IPSSs) were stable at 1 year.
  • Complications included two urinary tract infections and one episode of acute urinary retention.

El Fegoun et al. conclude that, “Hemi-prostate ablation with HIFU can be safely performed in selected elderly patients with adequate long-term cancer control and low complication rates.”

It is clear that focal HIFU (when conducted by appropriately skilled physicians) does offer a reasonable treatment option for appropriately selected, older men. It is also clear that such therapy may not be truly curative in a significant percentage of patients who appear to meet the relevant criteria. However, if the treatment is able to defer the need for other, more invasive forms of treatment, for an extended period of time, this may well be “good enough” for a significant number of such patients. The key issue is going to be whether we are able to discriminate with accuracy between three groups of patients who may currently be considered as appropriate for treatment with focal HIFU:

  • Those who have low-risk but truly indolent disease, who meet all criteria for focal HIFU but who do not actually need treatment at all and would be best managed with active surveillance.
  • Those who appear to have low- or intermediate-risk disease, and who meet all other criteria for focal HIFU, but who actually have bilateral or more clinically advanced forms of prostate cancer and who are always going to be at high risk for progressive disease if treated with focal HIFU.
  • Those who really do meet the appropriate criteria for focal HIFU and who can therefore be treated with focal HIFU with potentially curative intent.

The approipriate identification of such patients is going to be important to the appropriate application of focal HIFU, focal therapy in general, and many other forms of first-line therapy for localized prostate cancer.

5 Responses

  1. I am surprised that the study included only 12 men as well over 1,000 HIFU are reported from Germany elsewhere.

    — The data indicate that probably all therapies for low risk cases are successful for 5 years.
    — A 100% survival rate after 10 years is certainly encouraging.
    — Not sure how valuable this information is statistically because of the very small number of patients involved.
    — I assume that the patient’s age is referring to the age of the beginning of the treatment.
    — Average or mean. Which one is it? Do we know?

    Either way, an encouraging study.

  2. Wolfram:

    Please note that this study is exclusive to focal therapy patients (not whole-gland HIFU patients). Yes, the patient ages refer to ages at the time of treatment, and they are means — at true “average” (not medians).

  3. I understood the focal therapy part. This makes the results even more promising as (a) focal therapy became more and more controversial, (b) you could expect even better results for HIFU to the entire gland. It would be interesting to find out if the recurrence was confined to the the lobe of the treated volume only. This should give insight on the choice of focal versus “complete” treatment.

  4. Wolfram:

    I am not sure that your statement that “you could expect even better results for HIFU to the entire gland” is actually justified by the available data. I don’t think that that sort of leap of faith is necessarily a good idea. HIFU to the entire gland appears to be associated with a higher risk for complications than seen in this study too. What this study does show is that focal therapy was effective for 5 years in a high percentage of this particular study population, and less effective at 10 years — although no patients died of prostate cancer or demonstrated clear evidence of metastatic disease at 10 years of follow-up.

  5. However, since I haven’t read otherwise, HIFU is not yet approved as a treatment option in the U.S. in any form other than in continuing (?) trials.

    The focal option does appear promising for those comfortable with focal treatment, and with HIFU, it appears salvage treatment can be a broader application of HIFU. However, as stated by sitemaster, that broader application that would obviously include the entire prostatic bed and its periphery may be fraught with other complications.

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