Cryotherapy is a viable alternative to radiation therapy and radical surgery that shows great promise. The traditional and accepted treatments for confined prostate cancer (cancer that has not spread outside of the gland) include radical prostatectomy (surgical removal) and radiation therapy. Unfortunately, these treatments can result in significant complications.
Specimens examined from radical prostatectomy often indicate that the cancer has already spread outside of the gland. The surgical procedure did not result in complete removal of the cancer from the patient. This is known as a positive surgical margin. It has been reported that up to 30% of all radical prostatectomy procedures demonstrate a positive surgical margin. This is usually the result of underestimating (understaging) the extent of the cancer prior to surgery.
Radiation therapy is associated with a significant failure rate. This rate is based on biopsy-confirmed recurrent tumor following treatment. Due to the less than optimal clinical outcome, and significant complication rates of the traditional treatment modalities, new more effective and less invasive options for the treatment of prostate cancer are being investigated.
Cryoablation of the prostate involves the controlled freezing of the gland in order to destroy both cancerous and native prostatic cells. In 1968, Gonder and Soans introduced cryoablation of the prostate and achieved tissue necrosis (destruction). In the 1970’s, Bonny reported his cryosurgical experience with an open-perineal approach on 229 patients. The report revealed that cryosurgery patients had a probability of long-term survival equal to that seen in radical prostatectomy patients in each cancer stage.
However, a high rate of complications resulting from a lack of precise monitoring of the freezing process forced the abandonment of this technique. In 1988, Onik reported the feasibility of monitoring the freezing process using real-time ultrasound. In 1994, Dr. Duke K. Bahn and Dr. Fred Lee reported a further defined and tailored cryosurgical technique based on advanced transrectal ultrasound and advanced cryo technology, coupled with much improved interventional radiology skills.
Cryoablation of the Prostate
Candidates for cryoablation therapy should have accurate cancer staging with a transrectal ultrasound and prostate biopsy prior to the procedure. Knowledge of the exact location and size of the tumor, as well as the status of nearby structures, such as neurovascular bundles and seminal vesicles, proves crucial to the success of the treatment.
To achieve a high level of accuracy in staging, one must use state-of-the-art ultrasound equipment with color-Doppler and tissue harmonic capabilities. Patients may also have a bone scan and CT scan of the pelvis to rule out the possibility of distant metastases (cancer spread). Lymph node sampling is also recommended in selected cases. If distant metastasis or lymph node involvement is confirmed, the patient is not a candidate for cryosurgery.
Since current technology limits the amount of tissue that can be effectively frozen, the patient may be placed on three to six months of androgen ablation therapy (blockade of male hormone production). This therapy shrinks the prostate and cancer volume (downsize and downstage) prior to the cryoablation procedure.
Every patient is assigned to a team consisting of a board-certified radiologist and urologist for the cryosurgical ablation procedure and follow-up care.
Routine preoperative blood work, an EKG and a chest x-ray are required two days prior to cryosurgery. Most patients will spend one night in the hospital following the procedure.
Cryosurgery is performed under either general or spinal anesthesia. We typically make four to eight needle punctures in the perineum (skin surface between the rectum and scrotum) and, using ultrasound guidance, advance the needles to pre-selected locations in the prostate gland. The needle tracks will be dilated for insertion of the cryo probes used for the freezing. Precise temperature monitoring during the procedure is accomplished with multiple thermocouples placed at strategic locations surrounding the gland. After a warming device is placed to protect the urethra, the freezing process begins.
We apply a minimum of two freezes (two freeze and thaw cycles) for effective tissue destruction. The entire prostate, including the tumor and surrounding tissue, will be frozen.
The patient is discharged the next morning with a Foley catheter in place for drainage for two to three weeks.
You are required to return to the Institute three (3) months after cryosurgery for a follow-up ultrasound and PSA. For out-of-town patients, a PSA test result from your own physician will be adequate. A PSA test is recommended every three (3) months for the first year then every six (6) months for the next two years and yearly thereafter.
A biopsy is absolutely necessary at six (6) months, one (1) year and two (2) years and five (5) years after cryosurgery, or any time the PSA level rises over 0.5mg/ml.
Recently, Dr. Bahn and his colleagues published a seven-year outcome study based on 590 consecutive patients who underwent cryoablation therapy for the prostate cancer.
The overall biopsy proven disease free rate was 85.8%. If the stage of the cancer was T1-2 (cancer confined within the prostate), it was 88.7%, and if the stage was T3-4 (cancer already spread to outside of prostate capsule, but no distant metastasis), it was 74%. The overall biochemical disease free rate (PSA < 1.0 ng/ml) was 76%.
Although cryoablation therapy of the prostate is subject to some of the same complications as a radical prostatectomy and radiation therapy, the cryo-related complication rates are relatively low. The major complication recorded is a fistula (connection between rectum and prostatic urethra), which occurred in 0.5% of the patients. It was experienced in the early learning period of the procedure. All patients except two who experienced this complication had failed radiation therapy prior to having cryosurgery.
Based on a patient questionnaire study, urinary incontinence (defined as the use of pad) was seen in 4.3% of patients who had no prior treatments for prostate cancer. It was reported as 11% after radiation therapy and 31% after radical prostatectomy. In Dr. Bahn’s study, most patients used one pad for a few drops/day as a protective measure. In the radiation failure group, the incontinence rate was significantly higher than in the virgin group.
Impotency is an expected side effect of this procedure. It is due to the intentional freezing of tissue outside of the prostate gland to kill cancer cells that may have already spread beyond the prostate capsule. The Dr. Bahn study showed only 15% of patients gained potency (defined as an erection firm enough for vaginal penetration) and an additional 23% men claimed partial recovery. These numbers are essentially the same as the radiation and radical surgery reports.
There were other minor complications which included: outflow obstruction in 9%; pelvic pain in 11%; scrotal swelling in 17%; penile numbness or tingling sensation in 14%. These usually resolved within three months after the cryosurgery.
96% of the patients surveyed stated that they would choose cryosurgery again if it became necessary.
Cryosurgery is effective as a primary treatment for prostate cancer.
Cryosurgery is a promising option as a salvage treatment for radiation failure patients, including seed implantation failure.
Complication rates are lower for cryosurgery than radical prostatectomy and comparable to radiation therapy.
Advantages of Cryosurgery
- Minimally invasive—no blood loss, no surgical incision, outpatient surgery.
- Favorable success rate (based on seven year follow-up) & complication rates.
- Short recuperation period.
- Procedure can be repeated if first cryosurgery fails
- Radiation therapy (external beam or seed implantation) or radical surgery are still an option if first cryosurgery fails.
- Costs less than half of the traditional treatment.
Disadvantages of Cryosurgery
- No long-term randomized multi-center studies.
- The procedure is highly operator-dependent.
For more details, please read the following papers written by Dr. Duke Bahn: