How does Cryotherapy work?
Cryosurgeons use 3-mm or smaller diameter cryoprobes supercooled with argon. Cancer cell death is essentially assured at forty degrees below zero Celsius even for a moment. If the center reaches that temperature, the outer core of the iceball may be substantially warmer and barely below zero. This limitation is overcome by “double freezing.” This takes advantage of the fact that cells swell during thawing. After being frozen once, they are thawed by reversing the probe temperature. This involves turning the argon off and turning the helium on for the opposite effect. As soon as the ice ball freezes, argon is turned on again and the procedure is repeated.
What are the risks associated with Cryotherapy?
As with any prostate cancer therapy, cryotherapy can cause side effects or damage to adjacent organs. The urethra running right through the middle of the prostate is most vulnerable. In the early days of cryotherapy it was often frozen and would literally slough or turn inside out. Its channel would remain, but the lining would at times melt away for a few weeks until it healed.
This complication has been largely eradicated by the use of a urethral warming catheter that circulates warm fluid through its chambers. Saline or salt water at approximately forty degrees Celsius (104 Fahrenheit) usually protects the urethra.
Damage is also minimized by precise monitoring techniques currently in place. Probes placed near vital areas of interest tell us when to reverse the cooling process. Helium begins to warm the tissues within seconds so that the ice ball doesn’t grow beyond its intended borders.
How is the procedure performed?
Enemas and something to clean the intestines and rectum such as magnesium citrate will be administered the day before the operation. An ultrasound probe is placed into the rectum to guide placement of all probes.
Temperature sensing probes are placed near the prostate to allow the surgeon to know when freezing has reached beyond the gland. Four or more cryoprobes are placed into position. Freezing begins slowly under ultrasound and computer monitoring. When the ice ball reaches a lethal chill, the argon is turned off and helium is turned on to thaw the gland. The process is repeated as soon as it is thawed, and the entire procedure is completed within a couple of hours. The urethral warming catheter is sometimes left in place for an hour or so in the recovery room in order to minimize complications
Following surgery most men are permitted to return home within 24 hours, often on the day of the procedure. A catheter or suprapubic tube may remain in place for a week or longer. The punctures heal spontaneously within days.
Who is a candidate for Cryotherapy?
The most important thing to make you a candidate for cryotherapy is having cancer limited to the prostate or its immediate vicinity. Like other local therapies (prostatectomy and radiation), cryotherapy works only if cancer is contained in its targeted site.
Men with persistent cancer in the prostate following radiation therapy are obvious candidates. Because salvage prostatectomy (surgery following radiation therapy) is associated with significant complications, cryotherapy is appealing as a method of treating localized recurrent cancer without major surgery. Complication rates for cryotherapy following radiation are indeed higher than they are with cryotherapy as an initial treatment, but appear to be lower than the rates with salvage prostatectomy.2
Men with large prostates—measuring greater than 50-75 grams on ultrasound—are harder to treat. It is difficult to fully freeze all the tissue when the gland gets bigger than that. Those within about 10-15 grams of that volume can reach it by taking hormonal ablation.
Cryotherapy at present is appropriate only for men who understand they will probably not have spontaneous erections following treatment. These men may still be sexually active if they use treatments, but very few will have normal erections without such assistance. Interestingly, because the nerves are frozen instead of severed, a very small number of men will recover natural erections even two years following treatment. However this is the exception and most men will not.
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