Subtotal focal therapy for prostate cancer: Not ready for prime time

September 1, 2008

Focal cryotherapy, defined as less than complete ablation of the prostate gland with ice, potentially offers targeted local cancer control, preserving sexual potency and urinary continence in patients whose cancer is believed to be unilaterally clinically significant.

Two abstracts from this year's AUA annual meeting attempted to identify the best candidates for subtotal ablative treatment (see, "Research sets stage for subtotal focal ablation of PCa").

The first study, from New York University (NYU), compared pathologic and oncologic outcomes after radical prostatectomy among men with focal pathology-proven unilateral versus bilateral disease. On final pathology, 311 men had unilateral disease and 1,147 had bilateral disease. Men with unilateral disease had significantly lower rates of extracapsular extension, seminal vesicle invasion, and Gleason score ≥7 compared to those in the bilateral group. Given a 3-year median follow-up, the bilateral group had a significantly higher rate of biochemical recurrence.

Although both sets of authors seemed very encouraged by their data, I suggest that we proceed with caution. Both studies highlight significant shortcomings of subtotal focal ablation techniques for clinically localized prostate cancer. In their small study, the M.D. Anderson researchers noted that the median number of tumor foci in the prostatectomy specimens was three (range, one to eight); an application of either template would leave untreated prostate cancer in the majority of men. Additionally, the NYU researchers revealed that the vast majority of men in their chart review had bilateral prostate cancer, again raising questions about the likelihood that subtotal ablative therapy would adequately treat these cancers.

Having recently served on the AUA Best Practice Panel evaluating cryotherapy for the treatment of localized prostate cancer, I was surprised at the paucity of objective data on the oncologic efficacy of this technique. Our panel had no level 1 data on which to evaluate it, and the data on the efficacy of subtotal focal therapies were almost nonexistent.

I would certainly agree that research into new ablative techniques is sorely needed. In my opinion, however, these techniques should not be widely adopted based on ease of application, reimbursement, or availability without randomized trials comparing the techniques to established treatments such as radical prostatectomy and radiation therapy. Only then will urologists be able to appropriately counsel patients about the most appropriate approach (active surveillance, surgery, radiation, ablative techniques, chemotherapy, or hormonal therapy), given the patient's clinical parameters, overall health, and individual desires.

Dr. Thrasher, a member of the Urology Times Editorial Council, is professor and chair of urology, University of Kansas Medical Center, Kansas City.