Prostate Cancer
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- Prostate Cryoablation
- Radical Perineal Prostatectomy
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Prostate Cryoablation
The application of "cold" for medical purposes can be traced back to the Egyptians, who were believed to have used cold water for pain relief. More formal use of freezing techniques for medical purposes dates to 1865, in Great Britain, in papers by Arnott. The first application for freezing the prostate (prostate cryoablation) was published by Dr. Ruben Flocks, who in the 1970's described open perineal cryotherapy for prostate cancer. Because of severe rectal, urethral and sphincter toxicity, the technique was largely abandoned.
The modern era of cryoablation began in the 1990's with the appearance of the 3mm cryoprobes. These small probes, in combination with trans rectal ultrasound imaging have allowed for improved targeting and control of the ice ball size. With the advent of the 1.47mm probes as well as the use of thermocouples for better temperature monitoring, the morbidity has decreased even more.
Principles
It is well known that when human tissue is exposed to temperatures below freezing that tissue damage occurs. With temperatures falling to -7° to -10° C extra- cellular water begins to crystallize. This in turn increases the concentration of electrolytes in the extracellular fluid and begins to draw water from inside the cells. As the temperature drops to °-15C intracellular crystals begin to form. Cell membranes are damaged, and cells are destroyed. When tissue is cooled to -40°C all metabolic processes stop.
Cryoablation in Clinical Practice
The original indication for cryoablation of the prostate was for salvage therapy in men who had failed either external beam radiotherapy, or brachytherapy. With the introduction of the smaller cryoprobes, and the coincident decrease in post freezing morbidity, the indications have been extended for primary treatment as well. Generally speaking, men who have locally advanced prostate cancer, without metastatic disease may be good candidates for primary therapy, as are those who either refuse radiation therapy or are poor candidates for radical prostatectomy. The most common use is for men who have failed external beam radiation therapy, or brachytherapy.
The procedure is usually done as an outpatient. One day prior to the procedure, the patient is instructed to start taking a quinolone antibiotic (levaquin or cipro), take laxatives to clean out the bowel, and assume a low fiber diet. On the day of the procedure, either general or spinal anesthesia is required. With the patient in lithotomy position, a urethral warming catheter is placed, as well as the cryoprobes. These 17 gauge needles are placed in the skin between the scrotum and rectum, under ultrasound guidance, much the way that seeds are placed for brachytherapy. Two freeze-thaw cycles are generally used, after which a foley catheter is placed. The catheter will stay in place for 5-7 days.
Complications of cryoablation of the prostate are generally local, and include urethral sloughing, incontinence, infection, penile numbness, and erectile dysfunction. The incidence of incontinence is 1-2% in primary cases, and slightly higher in radiation salvage cases.
Results
The PSA will rise sharply during the immediate post freeze period, and should not be checked. This elevation is thought to be due to the release of intracellular PSA, at the time of cell destruction. The PSA will usually nadir at 3 months. Ideally, the nadir will be <0.4. In one 7-year study, the biochemical disease free survival rate for low grade, intermediate, and high grade prostate cancers, was 61%, 68% and 61%. When the PSA nadir point was placed at <1.0 the rates were 87%, 79%, and 71%.
With the new smaller cryoprobes, the morbidity of cryoablation of the prostate has become much more acceptable, not only for salvage treatment, but primary treatment as well. Research is currently on going with an eye towards potency sparing as well as possible focal cryoablation similar to "lumpectomy".
To determine if you are a candidate for cryoablation, speak to your physician. We pride ourselves in realizing that one size does not fit all. We are able to offer all of the latest treatments for prostate cancer, and will attempt to help you decide what is best for you based on your age, stage and grade of prostate cancer, as well as your other medical problems.