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Prostate Cancer: Minimally Invasive Treatment Options
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Submitted By: Duke Bahn
Article by Duke K. Bahn, M.D.
Cryotherapy
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 50-60% 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 50-80% failure rate. This rate is based on biopsy-confirmed recurrent tumor following treatment. Due to the limited effectiveness of the traditional treatment modalities, new more effective and less invasive options for the treatment of prostate cancer are being investigated.
Cryotherapy is an emerging alternative that shows great promise.
HISTORY
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 PROSTATE
Pre-operative staging: Candidates for cryoablation therapy should have accurate cancer staging with a transrectal ultrasound and prostate biopsy (staging biopsy, not random 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 capability. Patients will 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.
Pre-operative medication: Since current technology limits the amount of tissue that can be effectively frozen, the patient is 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.
Team Approach: Every patient is assigned to a team consisting of a board-certified radiologist and urologist for the cryosurgical ablation procedure and follow-up care.
Cryosurgery: Routine preoperative blood work and a chest x-ray are required on the day 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.
Follow-up: Patients are required to have PSA three (3) months after cryosurgery. A PSA test is recommended every six (6) months for three 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.
CLINICAL STUDIES
Recently, Dr. Bahn and his colleagues published 7-year outcome study base 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%.
Complications: Although cryoablation therapy of the prostate is subject to some of the same complications as radical prostatectomy and radiation therapy, the cryo-related complication rates are relatively low. The most major complication recorded is a fistula (connection between rectum and prostatic urethra), which occurred in 0.5% of the patients. 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 (1) and 31% after radical prostatectomy (2). 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 significant 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. Our study showed only 15% of patients gained potency (defined as a firm erection 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. (1,2).
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.
Conclusions
1. Cryosurgery is an effective form of prostate cancer treatment.
2. Cryosurgery is a promising option in radiation failure patients, including seed implantation failure.
3. Complication rates are lower for cryosurgery than radical prostatectomy and comparable to radiation therapy.
1) Jonler et al. Urology 1994.
2) Fowler et al. Urology 1993
ADVANTAGES OF CRYOSURGERY
1. Minimally invasive: no blood loss, no surgical incision, outpatient surgery.
2. Favorable success rate (based on seven year follow-up) & complication rates.
3. Short recuperation period.
4. Procedure can be repeated if first cryosurgery fails
5. Radiation therapy (external beam or seed implantation) or radical surgery is still an option if first cryosurgery fails.
6. Costs less than half of the traditional treatment.
DISADVANTAGES OF CRYOSURGERY
1. No long-term randomized multi-center studies.
2. The procedure is highly operator-dependent with steep learning curve.
Side view of prostate: Each cryoprobe creates an oval shape ice ball (blue color). We use up to 8 cryoprobes to cover the entire prostate.
Brachytherapy (Radioactive Seed Implantation)
INTRODUCTION
Brachytherapy is a form of radiation treatment in which tiny pellets containing radioactive material, such as Iodine-125 or Palladium-103, are implanted directly into the tumor-containing organ. This form of radiation therapy has long been used in other types of malignancies including cervical, breast, endometrial as well as head and neck cancers.
Brachytherapy offers the appealing concept of delivering high doses of radiation to the prostate while limiting the radiation dose to the adjacent organs.
HISTORY
Brachytherapy of the prostate dates back to 1911, when Pasteau published the first case in medical literature.
Utilizing a technique rather crude by today’s standards, Pasteau used a catheter to insert radium into the prostate urethra. Although the results showed fairly good local control of the cancer, the complications were too high to be considered acceptable.
Dr. Flock a urologist in Iowa, developed a technique using colloid gold, injecting it into the prostate for treatment. With the advent of high-energy linear accelerators, the interest in prostate brachytherapy waned.
Dr. Whitmore introduced an open brachytherapy method in 1972, using Iodine-125 or gold-198. Because the seeds were not always placed uniformly, the clinical results were less than satisfactory and the complication rates related to the surgical procedure were too high and unacceptable.
These early failures, to a large degree, were due to the fact that they were performed utilizing blind approaches. Imaging technologies, such as transrectal ultrasound, crucial for seed implantation, were not yet available. Some researchers tried temporary implantation with iridium-192 using an open surgical field, but they were still unable to visualize the internal structures of the gland. This technique was also burdened by the limitations of a blind approach. Precise placement of seeds is a crucial factor in the success of brachytherapy.
Without the benefit of modern day imaging techniques, accurate placement of the radioactive seeds was not attainable
In the early 1980s, the old concept of brachytherapy was revisited. Improved imaging technologies made the procedure more feasible. The most important of these were transrectal ultrasound (TRUS) and computerized tomography (CT). These new technologies allowed a non-surgical, uniform seed distribution into the prostate through needle punctures. With recent developments in computer software, TRUS has become the most commonly used modality for seed implantation procedures. However, the results can be highly operator-dependent.
CANDIDATES FOR BRACHYTHERAPY (SEED IMPLANT)
In determining who is a candidate for seed-implant therapy, there are several factors that must be considered.
The patient’s general state of health is a very important factor in determining which form of therapy should be chosen. Since this procedure is only minimally invasive, it is better tolerated than the more aggressive surgical procedures. The age of the patient is also important for this same reason. Therefore, an older patient that requires treatment may consider brachytherapy as an option.
Accurate staging of the tumor is mandatory before considering brachytherapy. A good color Doppler Ultrasound examination with staging biopsy is key to the accurate staging. Patients with early-stage, small-volume tumors are the best candidates for this procedure. Treatment with implants alone (either iodine-125 or palladium-103) is usually adequate for early stage small volume prostate cancer. For larger volume tumors, brachytherapy is usually performed in combination with additional external-beam radiation.
Younger patients with early small volume tumors may also choose brachytherapy because of the lower complication rates. This is especially true when impotency is a major consideration. Nevertheless, concerns over impotency should not allow the tumor treatment to be compromised. There are newer drug therapies that will allow impotent men to regain erections.
The treatment decision is a highly personal one that involves both medical, personal and life-style issues. The most important first step is that the patient needs to have his tumor accurately staged. Under staging (underestimating) a cancer is the most common reason for patients choosing inappropriate treatment options.This often leads to subsequent treatment failures.
IODINE-125 SEED IMPLANT ALONE CRITERIA
Tumor stage: less than or equal to T2a
Gleason grade: less than or equal to 6
PSA: less than or equal to 10
If prostate volume is more than 40 cc, pre-operative Androgen Ablation (Hormone) Therapy
(AAT) for 3-6 month duration to downsize the prostate volume.
PALLADIUM-103 OR IODINE-125 SEED IMPLANT WITH EXTERNAL BEAM TREATMENT CRITERIA
Tumor Stage: T2b, or T3a
Gleason grade: equal or over 7
PSA: over 10, but less than 30
All patients get 3-6 months of Androgen Ablation Therapy
The gland volume after AAT must be less than 40 cc
PROCEDURES PRIOR TO SEED IMPLANT
1. A precise prostate volume study: utilizing a dedicated transrectal ultrasound machine, this procedure is performed to create a road map for seed implantation. This is usually done 2-3 weeks before treatment. This study is transferred to a computer treatment program that determines the optimal number of seeds, needles and the distribution in the prostate in order to achieve the proper dose.
2. Routine pre-operative tests (Blood test, EKG, chest X-ray etc.) will be done a few days before the treatment.
Specific instructions will be given to you regarding diet and bowel prep
PROCEDURES DURING SEED IMPLANT
1. Unless there are contraindications (preventing factors), the procedure is performed in the operating room under spinal or general anesthesia.
2. An ultrasound probe is inserted into the rectum to image the prostate. The prostate is continuously visualized during the course of the procedure.
3. Based on the planning map, an average of 60-120 seeds are placed in the prostate through a needle that is placed through the perineum (skin between the rectum and the scrotum). The ultrasound guidance provides for precise and accurate positioning of the seeds.
4. Intra-operative real time dosimetry programs identify a radiation field on the computer screen any time a seed is placed in the prostate during the procedure. If a cold spot (poor radiation field) is detected, an extra seed is placed to correct the radiation distribution. Therefore, near perfect implantation is achieved.
5. At the end of the procedure, a catheter is temporarily inserted into the patient’s bladder to assure adequate drainage of urine. The entire seed placement procedure takes about one hour.
PROCEDURE AFTER IMPLANT
1. The patient is transferred to a recovery room and remains there approximately two hours with an ice bag placed at the needle entry site in the perineum. This is done to reduce local swelling. The Foley catheter is removed after the anesthesia has worn off and the patient has regained urinary control. Occasionally, the catheter may be left in overnight.
2. The patient is usually discharged that same day. However, it is strongly recommended that he not drive himself home. There are no diet restrictions. Heavy lifting and/or strenuous exercise are prohibited for approximately two weeks.
FOLLOW-UP SCHEDULE
The patient is required to have a PSA test every 3 months for the 18 months after the procedure, followed by one test every 6 months for a period of five years.
Biopsies should also be performed at 24 and 60 months after the procedure, or any time the PSA level rises at two consecutive occasions.
RADIATION SAFETY
Potential dangers of radiation to the family members are almost non-existent. Iodine-125 emits very low energy radiation, which is mostly contained in the region of the prostate. However, small amounts of radiation may escape from the prostate and travel a short distance. It is also possible for very small amounts of radiation to escape the body when a patient passes a radioactive pellet through the urine. For this reason, it might be prudent to avoid close contact small children or pregnant women during the first two months following implantation.
CLINICAL OUTCOME AND COMPLICATIONS
Recent data (Ragde, Cancer, July, 2000), 12 years follow-up data, shows 66% biochemical disease free rate (PSA < 0.5 ng/ml). Dr. Bahn’s data, containing more advanced cancer patients than Ragde’s study, also showed 67.5% biochemical disease free rate. When the PSA < 1.0 ng/ml is used as a criterion for disease free status, it was 86%. The results are very similar to cryotherapy statistics. However, it should be noted that the patient selection process was more stringent in seed implant group. Seed implantation therapy is only offered to a select group of patients who have small-volume, early-stage cancer.
Complication rates are generally lower in brachytherapy than with other modalities and comparable to cryotherapy.
Complications include proctitis, cystitis, incontinence and rectal bleeding. Current literature reports that significant rectal complications can occur in 5-10% of patients and urethral complications can occur in 10-14%.
It is common to experience problems with urination for a few months after seed implantation. Various degrees of impotency are also common after the procedure. The reported impotency rates are in the 20-30% range. However, there is also a correlation to the patient’s age and general state of health.
As with cryotherapy, the brachytherapy procedure is highly operator-dependent. If a patient is considering brachytherapy, he should look for the following:
1. An institution that utilizes the highest quality color-Doppler ultrasound equipment
2. Intra-operative real time dosimetry capability
3. Physician experience of a minimum of 50 patients.
INSERT IMAGE HERE
Brachytherapy performed with intra-operative dosimetry capability. Green line (100% of planed radiation dose) covers the entire prostate. No unnecessary radiation is seen in rectum (black round circle below the prostate). There is also no cold spot (poor radiation) inside of the prostate.
Duke K. Bahn, M.D.
Medical Director,
Prostate Institute of America,
Community Memorial Hospital
Ventura, CA 93003
888-234-0004
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