Researchers from Calgary have reported that outcomes of treating stage 1-3 with cryosurgery were equivalent to outcomes following radiation therapy. The details of this randomized trial were presented at the 2007 meeting of the American Urological Association.

Cryosurgery was first used to treat prostate cancer in the early 1970s, but it was not until 1993, when the results from percutaneous ultrasound-guided cryosurgery were published, that the potential advantages of this treatment became apparent. Changes in equipment and techniques have improved the results of cryosurgery in both tumor control and lower morbidity. Ultrasound-guided percutaneous transperineal placement of the cryoprobes allows monitoring of freezing in real time. Monitoring temperature at critical locations, separating the rectum and prostate by saline injection, and using argon gas rather than liquid nitrogen-based equipment have improved results and lowered complication rates. The technique is reported to produce outcomes similar to those obtained with brachytherapy and three-dimensional conformal radiation. Advantages of cryosurgery include the ability to re-treat patients without added morbidity and to treat salvage post-radiation patients with acceptable results and morbidity. There is also the possibility that "nerve-sparing" cryosurgery is possible.

Up until the now there have been no reports of randomized trials comparing cryosurgery to other treatment modalities for local prostate cancer. In fact, this may be the first randomized trial ever comparing two different therapies for localized prostate cancer. For instance there are no randomized trials comparing radical prostatectomy with any form or radiation therapy. In fact the current trial was stopped after the accrual of 244 patients due to lack of enrollment. Only one third of patients asked to participate in this trial actually did so.

This study included 244 patients with stage 1-3 prostate cancer who were randomly allocated to receive external beam radiation therapy or cryoablation. The median follow-up of this study is 73 months. The main findings are presented in the following table.

These authors concluded that randomized trials could be performed in men with localized prostate cancer, but are difficult. They also concluded that cryosurgery was as effective as radiation therapy for the treatment of localized prostate cancer.

Comments: Randomized trials of treatments for localized prostate cancer have been non-existent until this study. The main reason for poor accrual is that physicians have an occupational bias which is transferred to patients. This situation will undoubtedly continue with non-randomized comparisons being the norm. However, cryosurgery appears to be an increasing acceptable therapy for localized prostate cancer. 

References:  Donnelly BJ, Saliken JC, Brasher P, et al. Randomized controlled trial comparing external beam radiation and cryoablation in localized prostate cancer. Proceedings of the American Urological Association of 2007; Abstract #1141. http://www.abstracts2view.com/aua/authorindex.php

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