Is there a role for cryoablation of the prostate in the management of localized prostate carcinoma?
It is impossible to adequately answer the question of whether there is a role for CSAP in the management of localized prostate carcinoma without considering the relative advantages and limitations of using other therapies to manage this disease (radical prostatectomy, radiation therapy, hormonal therapy, brachytherapy, expectant observation, and so on). Obviously, this is beyond the scope of this article. It is probably fair to point out, however, that the management of localized prostate carcinoma in the United States is generally quite controversial at the present time, and that despite a considerable amount of data pertaining to these therapeutic alternatives, it is difficult to discern a standard approach that can be broadly applied for all men with this disease. Therefore, if an absence of consensus on the management of localized prostate carcinoma does exist, it seems evident that investigations into alternative therapies are justified, and the preliminary results and efforts investigating CSAP fall well into this paradigm. In this context, several points can be made based on the available information. Significant numbers of patients who undergo CSAP can sustain undetectable levels of PSA for durable periods of time (more than 24 months). Thus, on a clinical level it seems possible to ablate the entire prostate with percutaneous CSAP, although rates of achieving this may be lower than originally anticipated. The reasons for persistence of carcinoma post CSAP are likely technical and related to the difficulties in determining the effective probe placements, number of probes to be used, number of freeze-thaw-freeze cycles to be used, and so on. Previous radiation exposure appears to confer an increased risk of CSAP-related morbidity, with incontinence, tissue sloughing, and rectal injury most prominent. Among nonradiated patients, incontinence is rare, and the most prominent postoperative concern involves BOO/tissue sloughing in a minority of patients. The longest follow-up data available on CSAP suggests that for patients with nonmetastatic prostate carcinoma, CSAP is associated with persistence of carcinoma in only 25% of patients. This compares favorably with the available biopsy data following external beam radiotherapy, in which most reports document positive biopsy results ranging between 30% and 100%, with the majority in the 40% to 50% range. Notably, the positive biopsy rate among patients with stage T3 disease following CSAP at 2 years can be less than 30%, which compares very favorably with previously reported positive biopsy result for these patients following external beam radiation therapy, which ranged between 40% and 100%. The management of patients with persistent carcinoma following CSAP poses fewer concerns to physicians than for those with persistent carcinoma following radiation therapy. Given the number of patients with prostate carcinoma who currently undergo radiotherapy as primary management, these data indicate that CSAP can now be considered a very viable therapeutic alternative for selected patients. With standardizations of technique as well as improved modifications in equipment, these preliminary CSAP results may well improve steadily in the near future. In the absence of randomized, comparative trials, it is difficult to draw meaningful comparisons between CSAP and radical prostatectomy. Based on available information, CSAP appears to be associated with a much lower incidence of stress and total incontinence than is radical prostatectomy. The rates of impotence following CSAP are somewhat comparable to those seen after radical prostatectomy, with wide variation among individual series. For patients who would be ideal candidates for radical prostatectomy (for example, less than stage T2c disease, PSA less than 10 ng/mL, and Gleason score of 7 or less), several authors have noted that the positive biopsy rate between 6 and 12 months is less than 10%.
Long
J P
JP
Department of Urology, Tufts University School of Medicine, Boston, Massachusetts, USA.
D001706:Biopsy; D002278:Carcinoma in Situ / Q000276:immunology / Q000473:pathology / Q000601:surgery*; D003452:Cryosurgery; D003627:Data Interpretation, Statistical; D006801:Humans; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000276:immunology / Q000473:pathology / Q000601:surgery*
D017430:Prostate-Specific Antigen