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Cryoablation for Prostate Cancer
Prostate cancer is one of the most common forms of cancer in men and some of its traditional treatments can result in serious complications. However, cryoablation is an emerging alternative that shows great promise. What does this new treatment entail? What are its advantages and disadvantages? The following information should help answer those questions and more.
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What is cryoablation?
Cryoablation is a form of cryotherapy for the prostate that involves the controlled freezing of the prostate gland in order to destroy cancerous cells. The damage caused by freezing occurs at several levels: molecular, cellular and whole tissue structure. Important factors influencing freezing injury are the rate of temperature reduction after the initiation of freezing, the time cells remain frozen and the subsequent heating rate during thawing.
The cells are not the only structures damaged during freezing. During cryoablation of the prostate, the surrounding connective tissue (stroma) and the smallest blood vessels (capillaries) are damaged and subsequently have an inadequate blood supply that is believed to slow the growth of cancer.
Who are the most suitable candidates for cryoablation of the prostate?
Suitable candidates for this procedure are patients who have organ-confined prostate cancer or those who have minimal spreading beyond the prostate.
How is the procedure performed?
Under anesthesia, an ultrasound probe is guided into the rectum. The prostate is imaged and its dimensions measured. An aiming grid software program is then activated and images of the prostate are projected on a screen. Under continuous monitoring with ultrasound imaging, cryoablation probes are placed at predetermined sites within the prostate. The freezing starts at the front part of the prostate by activating the front probes, followed by the middle and finally the back probes. This sequence allows continuous monitoring (by visualizing the freezing process through the transrectal ultrasound). Two freezing cycles are usually done. Between them, the prostate is allowed to thaw either passively or actively by using helium gas. If the prostate is more than 26 to 27 mm. long, an apical pullback maneuver is usually done to freeze the lower part of the prostate. Double freezing is performed again. Each of the commercially available cryosurgical systems has a different type of probe and placement strategy, but all aim to freeze the prostate, tumor(s) and surrounding tissue — except the urethral area. By keeping the urethra warm during prostate freezing, the urethral wall remains viable. This is important, as it minimizes the risk of urethral damage, obstruction and urinary incontinence. Using a flexible cystoscope, the bladder and urethra are examined meticulously for evidence of injury. If a probe is found piercing the urethra it is repositioned. A suprapubic catheter (a small catheter that is pierced into the bladder through a small opening in the lower abdomen) is inserted and secured in place by a suture. The urethral warming catheter is introduced through the urethra with its end in the bladder. During the procedure, the bladder is kept nearly full by keeping the open suprapubic catheter at a slightly higher level than the bladder. The urethral warming catheter keeps the urethra warm throughout the procedure and is kept active for about 20 minutes after complete thawing to prevent the urethra from freezing.
What can be expected after treatment?
The patient is usually kept overnight, allowed some food and encouraged to walk. The patient is usually discharged the next morning with a catheter in place for drainage.
The patient can attempt to urinate at first desire. Most patients are able to urinate in about 10 to 15 days but some may require longer recovery periods. When the patient is able to urinate well and empty the bladder satisfactorily, the suprapubic catheter is removed. Some surgeons use a urethral catheter instead of the suprapubic catheter. In that case, the urethral catheter is removed seven to ten days and trial unination is attempted. If the patient is unable to urinate, the catheter is reinserted for a few more days. Oral antibiotics are usually given for 10 to 14 days. Other symptoms and signs the patient may experience are generalized fatigue that usually persists for seven to 10 days, urethral discharge, scrotal swelling, numbness at the tip of the penis, passage of flecks of tissue, pain or burning sensation during urination and increased urinary frequency and/or urgency.
A PSA test is usually done at three months. Also, a prostatic biopsy may be done at three to six months to assess for prostate destruction and absence of viable cancer cells especially if PSA level is detectable. If the biopsy proves negative, PSA measurements are obtained monthly for one to two years, then every six months for the next one to three years and every year thereafter.
What type of results can be expected?
Five U.S. institutions reported their experience with the use of cryoablation. The results were compared to those of conformal radiotherapy and brachytherapy. Patients with a previous history of failed radiotherapy were excluded and androgen deprivation was determined and categorized separately. Patients were classified as low risk, moderate risk or high risk according to the cancer characteristics (stage of the disease, Gleason grade and PSA level). The procedure was not consistent at all institutions. Differences included the number of probes used, number of freeze cycles per patient, length of apical pullback maneuver, real-time monitoring during freezing and the system used for freezing. A total of 975 patients were studied, of whom 238 were low risk, 321 were moderate risk and 385 were high risk; risk was not determined in 38 patients. The five-year rate for non-rising postoperative PSA levels for low and medium risk patients ranged between 60 and 76 percent and for high-risk patients it was 41 percent. Only about 18 percent of the patients were found to have a positive biopsy following the procedure. These results are encouraging and may place cryoablation therapy between radical prostatectomy and radiotherapy in effectiveness.
What are the risks associated with this procedure?
New technological advances have resulted in a significant reduction of the rate of complications. Improved urethral warming devices have minimized urethral complications. Better spacing of the probes now contributes to the effectiveness and safety of the procedure. Improved monitoring of the freezing with transrectal ultrasound is also helpful. However, some risks still exist. Perhaps one of the most critical is the risk of urinary rectal fistula, which creates a channel between the prostate or the bladder and the rectum and may cause diarrhea due to urine in the rectum and possibly severe infection due to bacteria in the bladder. There is also a high incidence of erectile dysfunction. Other complications, although uncommon given technological advances, include urinary incontinence, urinary retention requiring transurethral resection of the prostate (TURP) and inflammation of the testicle. Almost all patients have a temporary need for a catheter to empty the bladder for an average of 15 days. Permanent, severe incontinence is rare (approximately 1 percent) and other rare complications include prostatic abscess and permanent penile numbness.
Frequently asked questions:
What are the advantages and disadvantages of cryoablation of the prostate?
Cryoablation therapy offers:
a minimally invasive procedure
favorable success rate and complication rates
a short recuperation period
procedure can be repeated if the first cryoablation has failed
radiation therapy or radical prostatectomy is still an option if the procedure fails
less than half the cost of the traditional treatment
The disadvantages are:
insurance may not cover this procedure
extensive experience and training by the surgeon are required
Is cryoablation therapy ever used after other prostate cancer treatments have been tried?
Yes. An important use of cryoablation therapy is for patients who fail or develop recurrence after radiation therapy.
Where can I get more information?
Prostate Specific Antigen (PSA).
Prostate Specific Antigen (PSA) (Zinio format).
Download the free Zinio reader or the free Acrobat reader.
Reviewed May, 2004
Common misspellings: prostrate
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Glossary Terms
abdomen:
Also referred to as the belly. It is the part of the body that contains all of the internal structures between the chest and the pelvis.
ablation:
Removal of diseased or unwanted tissue from the body by surgery or other means.
abscess:
An accumulation of pus anywhere in the body.
androgen:
Male sex hormone.
anesthesia:
Loss of sensation in any part of the body induced by a numbing or paralyzing agent. Often used during surgery to put a person to sleep.
antibiotic:
Drug that kills bacteria or prevents them from multiplying.
apical:
Used to describe the top of something.
bacteria:
Single-celled microorganisms that can exist independently (free-living) or dependently upon another organism for life (parasite). They can cause infection and are usually treated with antibiotics.
biopsy:
A procedure in which a tiny piece of a body part (tissue sample), such as the kidney or bladder, is removed (with a needle or during surgery) for examination under a microscope; to determine if cancer or other abnormal cells are present.
bladder:
The balloon-shaped pouch of thin, flexible muscle in which urine is temporarily stored before being discharged through the urethra.
brachytherapy:
Treatment for prostate cancer that involves the placement of tiny radioactive pellets into the prostate by utilizing ultrasound.
cancer:
An abnormal growth that can invade nearby structures and spread to other parts of the body and may be a threat to life.
capillaries:
Thin blood vessels.
catheter:
A thin tube that is inserted through the urethra into the bladder to allow urine to drain or for performance of a procedure or test, such as insertion of a substance during a bladder X-ray.
cellular:
Relating to small parts or groups.
continence:
The ability to control the timing of urination or a bowel movement.
cryotherapy:
During an operation, probes are placed in the prostate. The probes are frozen thus killing the prostatic cells.
cyst:
An abnormal sac containing gas, fluid or a semisolid material. Cysts may form in kidneys or other parts of the body.
cystoscope:
A narrow, tube-like instrument fitted with lenses and a light passed through the urethra to look inside the bladder. The procedure is called cystoscopy (sis-TAW-skuh-pee).
erectile:
Capable of filling with blood under pressure, swelling and becoming stiff.
erectile dysfunction:
Also known as ED or impotence. The inability to get or maintain an erection for satisfactory sexual intercourse. Also called impotence.
fistula:
An abnormal opening between two organs (between the bladder and vagina in women or the bladder and the rectum in men).
gene:
The basic unit capable of transmitting characteristics from one generation to the next.
gland:
A mass of cells or an organ that removes substances from the bloodstream and excretes them or secretes them back into the blood with a specific physiological purpose.
incontinence:
Loss of bladder or bowel control; the accidental loss of urine or feces.
infection:
A condition resulting from the presence of bacteria or other microorganisms.
inflammation:
Swelling, redness, heat and/or pain produced in the area of the body as a result of irritation, injury or infection.
invasive:
Having or showing a tendency to spread from the point of origin to adjacent tissue, as some cancers do. Involving cutting or puncturing the skin or inserting instruments into the body.
ions:
Electrically charged atoms.
penis:
The male organ used for urination and sex.
probe:
Small device for measuring and testing.
prostate:
In men, a walnut-shaped gland that surrounds the urethra at the neck of the bladder. The prostate supplies fluid that goes into semen.
prostatectomy:
Surgical procedure for the partial or complete removal of the prostate.
prostatic:
Pertaining to the prostate.
PSA:
Also referred to as prostate-specific antigen. A protein made only by the prostate gland. High levels of PSA in the blood may be a sign of prostate cancer.
PSA test:
Also referred to as prostate-specific antigen test. A blood test used to help detect prostate cancer.
radiation:
Also referred to as radiotherapy. X-rays or radioactive substances used in treatment of cancer.
radiation therapy:
Also referred to as radiotherapy or radiation. X-rays or radioactive substances used in treatment of cancer.
radical:
Complete removal.
radical prostatectomy:
Surgical removal of the prostate and seminal vesicles.
radiotherapy:
Also referred to as radiation therapy. High-energy rays are often used to damage cancer cells and stop them from growing and dividing.
rectal:
Relating to, involving or in the rectum.
rectal ultrasound:
A diagnostic test that uses very high frequency sound waves to produce an image of the rectum.
rectum:
The lower part of the large intestine, ending in the anal opening.
resection:
The surgical removal of a portion of a body part.
scrotal:
Relating to the scrotum, the sac of tissue that hangs below the penis and contains the testicles.
stage:
Classification of the progress of a disease.
stent:
With regard to treating ureteral stones, a tube inserted through the urethra and bladder and into the ureter. Stents are used to aid treatment in various ways, such as preventing stone fragments from blocking the flow of urine.
stroma:
The connective tissue that provides the framework of an organ or other anatomical structure rather than carrying out its function.
suprapubic:
An area of the central lower abdomen above the bony pelvis and overlying the bladder.
suture:
Surgical seam where a wound has been closed or tissues have been joined.
testicle:
Also known as testis. Either of the paired, egg-shaped glands contained in a pouch (scrotum) below the penis. They produce sperm and the male hormone testosterone.
tissue:
Group of cells in an organism that are similar in form and function.
transrectal ultrasound:
Also referred to as TRUS. This is a special kind of ultrasound test in which the sound waves are produced by a probe inserted into the rectum. In men, the structures most commonly examined with this test are the prostate, bladder, seminal vesicles and ejaculatory ducts.
transurethral:
Through the urethra. Several transurethral procedures are used for treatment of BPH. (See TUIP, TUMT, TUNA or TURP.)
transurethral resection:
Surgery performed with a special instrument inserted through the urethra.
transurethral resection of the prostate:
Also referred to as TURP. Surgical procedure where a lighted tube with an attached electrical loop is inserted through the urethra into the prostate. Serves as a diagnostic and therapeutic role in the treatment of bladder cancer.
tumor:
An abnormal mass of tissue or growth of cells.
TURP:
Also referred to as transurethral resection of the prostate. Surgical procedure where a lighted tube with an attached electrical loop is inserted through the urethra into the prostate. Serves as a diagnostic and therapeutic role in the treatment of bladder cancer.
ultrasound:
Also referred to as a sonogram. A technique that bounces painless sound waves off organs to create an image of their structure to detect abnormalities.
urethra:
In males, this narrow tube carries urine from the bladder to the outside of the body and also serves as the channel through which semen is ejaculated. Extends from the bladder to the tip of the penis. In females, this short, narrow tube carries urine from the bladder to the outside of the body.
urethral:
Relating to the urethra, the tube tha carries urine from the bladder to outside the body.
urge:
Strong desire to urinate.
urgency:
Strong desire to urinate.
urinary:
Relating to urine.
urinary frequency:
Urination eight or more times a day.
urinary incontinence:
Involuntary loss of urine associated with a sudden strong urge to urinate.
urinary incontinence:
Inability to control urination.
urinary incontinence:
Involuntary loss of urine associated with a sudden strong urge to urinate.
urinary incontinence:
Inability to control urination.
urinary retention:
Failure to empty the bladder totally.
urinate:
To release urine from the bladder to the outside. Also referred to as void.
urination:
The passing of urine.
urine:
Liquid waste product filtered from the blood by the kidneys, stored in the bladder and expelled from the body through the urethra by the act of urinating (voiding). About 96 percent of which is water and the rest waste products.
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