PROSTATE-SPECIFIC ANTIGEN AFTER CRYOSURGICAL ABLATION OF THE PROSTATE : Defining the Appropriate Response - 11/09/11
Résumé |
Cryosurgical ablation of the prostate is available at many centers in the United States as a treatment option for localized prostate cancer. Most centers performing cryosurgery quote good short-term success rates, with the majority of patients showing negative post-treatment biopsies and substantial reductions in serum prostate-specific antigen (PSA) levels.2 , 3 , 5 , 6 , 13 , 14 , 16 , 18 , 19 Follow-up of cryosurgical patients, however, is still very short, with only a few centers having published PSA or biopsy results at 2 years after the procedure. The durability of cryotherapy, therefore, is unknown, and the pathologic and PSA findings that constitute an appropriate response are not defined fully. Specific questions that need to be addressed include the significance of benign epithelial elements on an otherwise negative postcryosurgery biopsy, the significance of a low but detectable PSA level after treatment, and the durability of the procedure.
After radical prostatectomy the pathologic specimen can be analyzed to determine the bulk and grade of tumor and the presence of extracapsular extension or positive surgical margins. PSA levels should be undetectable in patients considered cured after radical prostatectomy. With radiation therapy, assessment of treatment success is still a matter of debate. PSA levels usually remain detectable and biopsies of the prostate may show residual cancer, even if there is no biochemical or clinical evidence of disease progression.17 Long-term studies of irradiated patients, however, have shown that many patients achieve long-term remission of their cancer despite a low but detectable PSA level. A nadir PSA of less than 1 ng/mL after radiotherapy is associated with a 65% to 85% probability of being disease-free from PSA failure 5 years after radiation.10 , 12 An improvement in the ability to predict long-term cancer control after radiation can be enhanced if a reference range of PSA level less than 0.5 ng/mL is used. Others have argued for the use of reference ranges less than 2 ng/mL to predict control or cure of prostate cancer.9 As far as assessment of end points is concerned, cryosurgery may be closer to radiation therapy than to radical prostatectomy. As there is no pathologic specimen to examine and the gland has been destroyed in situ rather than removed, reliance is placed on follow-up biopsies of the prostate and serial PSA levels to determine success or failure.
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Address reprint requests to Peter R. Carroll, MD, Department of Urology, U–575, University of California, 513 Parnassus Avenue, San Francisco, CA 94143–0738 |
Vol 24 - N° 2
P. 415-420 - mai 1997 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.
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