Modern cryotherapy for prostate cancer started in 1988 when Dr. Gary Onik first described the ultrasonic appearance of frozen prostate tissue. Easy access to the prostate through the perineum and excellent visualization of the gland with transrectal ultrasound combined to demonstrate successful prostate ablation using needles placed with ultrasound guidance between the rectum and the scrotum with minimal morbidity. In 1999 the centers for Medicare and medical services (CMS) approved Medicare to cover percutaneous cryoablation of the prostate.
First generation machines used liquid nitrogen and five cryoablation needles to freeze tissue. They were inserted perineally between the rectum and the scrotum using a rectally placed ultrasound probe to direct needle placement. These machines were used in the 1990s. When the liquid nitrogen was turned off the tissue continued to freeze for a relatively long period of time. Second generation machines have been in use since 2000. They use argon gas to freeze tissue to -180 degrees Fahrenheit. Generally 6 probes are used. The area frozen per probe is smaller and when the argon gas is turned off the freezing effects on tissue stop almost immediately as compared to the liquid nitrogen machines. This gives more precise control of the tissue being ablated. Temperature sensors are placed in and outside the prostate to prevent damage to the surrounding tissues such as the rectum and the external sphincter. This helps prevent damage to the rectum and helps prevent incontinence. Nerve sparing procedures can be performed if the tumor is not near the neurovascular bundles. These bundles contain the nerves and blood vessels that go to the penis and control erections. They lie just a few millimeters from the edge of the prostate.
One limitation of cryoablation is that the gland can not be more than 50 grams in size. The ablative cryolesions are 2 cm in diameter and 2 to 4 cm long depending on the probe size. An advantage of cryosurgery is the urethral warmer which is placed at the beginning of the procedure. A thin rim of tissue is in the urethra is kept viable and helps reduce the incidence of tissue sloughing and stricture formation. Another major advantage of cryoablation is the ability to treat only the affected part of the prostate gland. This has been called the “male lumpectomy” or “nerve sparing” cryoablation. A final major advantage of cryoablation is that it does not affect surrounding tissues. If cryoablation needs to be repeated it can be easily repeated with no increase in morbidity, unlike radiation which can not be repeated due to excessive damage to the surrounding tissues, the rectum and the bladder. If the tumor recurs after radiation or surgery some other form of treatment must be pursued. If the tumor recurs after cryoablation it can be very easily repeated.
The cure rate is excellent. 90% of low risk early prostate cancers have a negative biopsy at 5 years. Even more advanced T3 lesions (bulky palpable tumors) have an 80% negative biopsy rate after cryoablation and this is superior to radiation and to radical prostatectomy in this group of patients. Unfortunately most of these cancers are too large to treat with cryoablation. Impotence is almost nonexistent with one sided cryoablation (10%) but with standard double sided cryoablation impotency is almost 90% because the nerves and the arteries that go to the penis are only a few millimeters outside the edge of the prostate and are frozen and damaged. Incontinence is 5% with standard cryoablation, the same rate as radiation therapy. With one sided cryoablation there is virtually no incontinence. Rectal damage and fistula should be far less than 1% with modern second generation equipment.
The MALE LUMPECTOMY or nerve sparing cryoablation is the only treatment available in the USA in 2010 that can treat the cancerous tissue and leave the non-cancerous tissue alone. This is similar to what happened in the 1970’s with breast cancer treatment. The standard of care if a breast cancer was found was to remove the entire breast. The standard of care today in most cases is to remove the cancerous part of the breast and to spare or leave intact the non-cancerous part of the breast. The cure rates are equivalent. This leaves a much more functional and much less disfigured breast and chest wall. A similar procedure can be done with cryosurgery of the prostate. A one-sided freeze can be done, the so called “male lumpectomy”. The freeze is performed only on the side where the tumor is located. This leaves a functional prostate intact in most men. This has almost no impotence because the nerves and arteries that supply the penis are preserved on the side that is not treated. It has almost no incontinence because the urinary sphincter is not damaged on the side that is not treated. The disadvantage of nerve sparing cryoablation or one sided cryoablation is that cancer can theoretically still occur in the untreated tissue. Because of this a saturation biopsy is performed on the side of the prostate that is being spared. This involves taking at least 12 or more biopsies of the side without cancer to be as certain as possible that there is not a small focus of cancer that was missed at the original biopsy. About one out of 4 times when a saturation biopsy is performed a small area of cancer will be detected that was previously missed.
SALVAGE CRYOABLATION can be performed when radiation fails after treatment for prostate cancer. There are three alternatives to treatment. The first alternative is salvage prostatectomy, or removal of the prostate. Most urologists do not recommend this form of treatment due to the very high complications of the treatment. Permanent urinary incontinence is as high as 35% in persons undergoing this procedure. This means wearing diapers for the rest of one’s life or undergoing further surgery to try to correct this problem. Also the rectum can be damaged causing a permanent connection or a fistula between the urethra and the rectum resulting in passing stool out of the urinary tract. This can require a permanent colostomy and possibly a permanent urinary catheter. This can happen in 5% to 10% of persons. Impotence is virtually 100%. Because of the high complication rate many urologists have offer the second alternative which is hormone therapy. This suppresses the cancer temporarily but does not cure the cancer. Long term hormone therapy can cause osteoporosis, muscle wasting and breast enlargement.
The third alternative after radiation therapy failure is one of the most successful roles for cryoablation. Salvage after radiation failure has a 60% cure rate if the PSA is 4 or less. If the PSA is between 4 and 10 the cure rate is 30%. If the PSA is more than 10 the cure rate is 10%. Incontinence is still only 5%. Impotence is 100%. Fistula or connection between the rectum and the urethra can occur in 1 to 2 percent of persons undergoing salvage cryoablation after radiation failure and this is due to the already damaged tissues from radiation treatment.
To learn more about cryoablation, visit these websites: www.cryocarepca.org. In 2008 the American Urologic Association has developed a Best Practice Policy Statement on Cryosurgery for the Treatment of Localized Prostate Cancer.
You will find it at http://www.auanet.org/content/guidelines-and-quality-care/clinical-guidelines/main-reports/cryosurgery08.pdf. These sites give a wealth of information on the successes and complications of this procedure, and its use as primary therapy for localized prostate cancer as well as its excellent success in treatment of radiation failure for prostate cancer.
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