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Prostate Disorders Special Report

A New Look at Cryosurgery

Also known as cryotherapy or cryoablation, cryosurgery is a minimally invasive treatment that kills cancer cells by freezing them. Cryosurgery is not a new prostate cancer treatment -- it's been used for more than 40 years, most commonly as "salvage" therapy in men whose cancer has recurred locally in the prostate after radiation therapy. But today, it's getting more attention as a first-line option thanks to technological advances in the tools used to perform the procedure. Nonetheless, it is not right for everyone. Here are some issues to consider before making your decision.

How Cryosurgery Is Performed -- The surgeon inserts a catheter containing warm saline into the urethra to protect it from the freezing temperatures. Next, thin needles called cryoprobes are inserted through the perineum (area between the scrotum and anus) and into the prostate. An ultrasound probe placed in the rectum allows the surgeon to see the prostate and surrounding tissue, which helps guide placement of the needles.

Freezing argon gas rapidly lowers the temperature of the cryoprobes to about -40° C. The extremely low temperatures create ice balls that freeze the entire prostate and some of the nearby tissue. After the prostate is frozen, it is thawed, and the freeze-thaw cycle is repeated again to reduce the chances that any cancerous tissue remains. The procedure takes about two hours. Often men go home the same day, although an overnight stay is sometimes required.

Issues and Concerns -- Although the American Urological Association considers cryosurgery an acceptable option for the treatment of newly diagnosed prostate cancer, it's been hard for urologists to give the procedure a whole-hearted thumbs up for a number of reasons.

  • First, the effectiveness of cryosurgery relative to radical prostatectomy and radiation therapies has not been well studied. Only one small head-to-head randomized trial comparing cryosurgery with another therapy (EBRT or external beam radiation therapy) has been published. The results, reported in Prostate Cancer and Prostatic Diseases, suggest that cryosurgery is less effective than EBRT. But this study was conducted in men with prostate cancer affecting the entire prostate or extending beyond it (stage T2c, T3a, or T3b). Emerging data indicate that in men with early-stage (T1 to T2b), low-risk prostate cancer, cryosurgery may be as effective as EBRT and brachytherapy.
  • Second, there are no long-term (10 years or more) data from studies in which investigators only used the most up-to-date equipment. Newer, third-generation systems, in use since 2000, use smaller probes and argon gas instead of liquid nitrogen, and they create smaller ice balls than older instruments. These and other refinements give the surgeon more control over ice-ball formation, improving the chances for complete destruction of the cancerous tissue while reducing the risk of adverse effects.
  • Another concern: Comparison of study results is difficult because there is no standard definition of disease recurrence when evaluating the effectiveness of cryosurgery. Some researchers define a recurrence following cryosurgery as a detectable prostate-specific antigen (PSA) -- the marker used to determine if cancer has recurred after prostatectomy. Others define it as consecutive increases in PSA -- the marker used to determine recurrence following radiation therapy. And to further complicate the issue, there are two ways of defining a PSA increase -- the American Society for Therapeutic Radiology and Oncology (ASTRO) definition (three consecutive increases in PSA) and the newer Phoenix definition (a PSA increase of 2 ng/mL).

Is Cryosurgery for You? According to the American Urological Association (AUA), cryosurgery is a treatment option for prostate cancer of any grade that is limited to the prostate and has not spread to surrounding organs, although results are best in men with PSA levels of less than 10 ng/mL and a Gleason score of 6 or below.

It may be a good choice for men who aren't able to have a radical prostatectomy because of, for example, obesity or a history of pelvic surgery. Cryosurgery may also be a reasonable option for men who cannot undergo radiation therapy for reasons such as a narrow pelvis, inflammatory bowel disease, previous pelvic radiation, or a rectal disorder. But the AUA notes that men with very large prostates are not good candidates, because the larger the prostate, the more difficult it is to cool the entire gland uniformly.

In some cases, the urologist may administer hormonal therapy to shrink the prostate before surgery. Although this has never been proven to increase the success rate, urologists have reason to believe that it might. Most men who have undergone a transurethral resection are poor candidates for cryosurgery.

Posted in Prostate Disorders on September 16, 2010

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