Prostate Seed Implant - PSI
Prostate seed implant or PSI is a procedure that is performed for the treatment of some patients with prostate cancer. The first PSI procedures at Pitt County Memorial Hospital in Greenville, NC, were performed by Dr. Koltis in conjunction with Dr. Dieter Bruno of Eastern Urological Associates. The procedure involves the placement of small “seeds” of radioactive material directly into the prostate gland, and it is performed in the operating room at PCMH. Typically, this involves an early morning admission to the hospital with the patient usually being discharged from the hospital on the same day or the day following the PSI.
Which men with prostate cancer might benefit from PSI?
Is prostate seed implant the only treatment necessary for management of prostate cancer?
How is the procedure performed?
What type of radioactive material is used for this procedure?
What procedures are necessary in preparation for a prostate seed implant?
Are there any restrictions of activity following discharge after the procedure?
Is there is any significant risk of complications?
How do I determine whether I may be a candidate
for a prostate seed implant?
Which men with prostate cancer might benefit from PSI?
The placement of radioactive seeds into the prostate is a treatment option that is best performed on patients with a low to moderate grade (well or moderately differentiated) adenocarcinoma of the prostate, who have a low to minimally elevated serum PSA, and a low risk of extension of the tumor outside of the prostate. The radiation oncologists at Carolina Radiation Medicine, and Dr. Dieter Bruno of Eastern Urological Associates work collectively to assess a patient’s suitability for a PSI procedure. The extent of tumor involvement in the prostate gland, the Gleason Score (assessment of the grade of the malignancy on the scales ranging from 2 to 10, with 2 being low grade and 10 being a very high grade tumor), the serum PSA (prostate specific antigen) level, and the general medical condition of the patient are taken into account when conducting an evaluation of a candidate’s suitability for PSI as a treatment option. In patients with a low to moderate risk of tumor involvement outside of the prostate capsule, or minimal extension outside of the prostate, the PSI procedure may be performed. Careful assessment of all of these features, in addition to biopsy proven documentation of malignancy is essential to evaluate a man’s suitability for this procedure.
Is prostate seed implant the only treatment necessary for management of prostate cancer?
This depends upon the likelihood of extension of the tumor beyond the prostate gland itself. PSI may be the only treatment necessary; however, if there is only a low to moderate risk of tumor extension beyond the prostate, or if the PSA is not significantly elevated (less than 10). In other situations treatment may include use of androgen blockade (administration of oral agents or hypodermic injections) used to suppress the effect of male hormone (testosterone) that is known to stimulate the growth of the prostate cancer. The need to administer these agents (such as Lupron, Zoladex, Eulexin, Casodex), and the duration of time over which they should be administered depends upon each individual’s situation. Suppression of male hormone (androgen blockade) may be necessary for a short time, such as three months, to as long as two years or more. As research continues and more information becomes available from large studies on the management of prostate cancer, the recommendation for the use of androgen blockade may be modified.
If there is moderate or high risk of tumor extension beyond the prostate, and a moderate elevation of the serum PSA, a PSI may be performed as a “boost” to deliver a high dose of cancer killing radiation to the prostate cancer initially, then followed by external beam radiation therapy (EBRT) that begins approximately 60 days following the implant procedure. External beam irradiation is conducted on an outpatient basis and consists of treatment five days per week. Depending upon the risk assessment and stage of an individual’s prostate cancer, a determination will be made as to whether a PSI alone (monotherapy) or multimodality therapy, which may include androgen blockade, and/or external beam radiation therapy, or both will be necessary.
How is the procedure performed?
The procedure is performed in an operating room and requires either a general anesthesia or a spinal anesthetic to be administered. After the patient is anesthetized and positioned appropriately, an ultrasound probe is inserted into the rectum and the size of the prostate gland, its exact location in addition to the location of the rectum, seminal vesicles, and bladder are accurately assessed. The actual volume of the prostate gland is then calculated.
A notebook computer containing the software program required to perform the calculations necessary to determine the proper location of the radioactive seeds is connected directly to the ultrasound machine. As the urologist and radiation oncologist assess the volume and location of the above-mentioned structures, the physicist or dosimetrist “captures” the information in the treatment planning notebook computer. A sophisticated computer program then is utilized to determine the proper placement of the needles through which the radioactive seeds will be implanted.
The radiation dose distribution displayed on the computer is then reviewed by the radiation oncologist and dosimetrist or physicist, and any necessary adjustment to the location of the seeds is then made and documented in the computer. After an optimized treatment plan is obtained, the urologist and or radiation oncologist will insert small hollow needles into the prostate through the perineum (space between the scrotum and anus). This allows the needles to be positioned to avoid placement of radioactive seeds into either the rectum or the bladder. The radioactive seeds (Iodine-125 or Palladium-103) are then deposited into the positions calculated with their location tracked on the computer. The exact location of each radioactive seed is observed on the ultrasound monitor, as well as on the treatment-planning computer. Since small variations in the position of the radioactive seeds always occur, the radiation dose distribution throughout the prostate gland is constantly updated on the treatment planning computer. This is referred to as “real-time” planning or “planning on the fly.” This allows constant and accurate updating of the actual radiation dose distribution, and allows for modification of the computer plan, if necessary, at the time of the placement of the individual seeds.
After all of the radioactive seeds are deposited into their proper position in the prostate gland, a final review of the radiation dose distribution is performed. If there are any areas in the prostate gland that do not receive an adequate dose of radiation, additional needles and seeds may be placed at that time. At the end of the procedure the hollow needles are removed, and the rectal probe is removed.
Small puncture sites may be visible in the skin of the perineum with a small amount of bleeding occurring at the puncture sites. This is easily controlled with the use of direct pressure. A drainage catheter is placed into the bladder during the procedure and is usually left in place until the patient has recovered adequately at which time it may be removed. In most situations, the catheter will be removed before the patient is discharged from the hospital, or it may remain in place with urine draining into a leg bag for one to two days. The need for the catheter to remain in place depends upon the amount of swelling that occurs within the prostate during the procedure.
What type of radioactive material is used for this procedure?
Radioactive seeds that contain either Iodine-125 or Palladium-103 are used for this procedure. The use of Palladium versus Iodine is determined by multiple features of the individual’s prostate cancer that have been mentioned previously. Palladium-103 (Pd-103) is typically used for a boost when external beam irradiation is planned to be given a couple of months following the implant procedure. Iodine-125 (I-125) is typically used both for individuals who do not require external beam irradiation, and for those who have low to moderate grade malignancies.
The entire procedure is performed while under general or spinal anesthesia. There is usually minimal discomfort in the region of the perineum and prostate after recovery from the anesthetic.
What procedures are necessary in preparation for a prostate seed implant?
A volume study will need to be performed within a few weeks prior to actual PSI procedure. This is conducted with the use of transrectal ultrasound and is performed in the urologist’s office. This preliminary volume study provides an estimate of the volume of the prostate gland. This is necessary to determine if the prostate is too large for a PSI procedure to be performed, and to provide information for the radiation oncologist to calculate the number of radioactive seeds that need to be ordered for the PSI. After this information is obtained, and the radioactive seeds are ordered, certain preadmission tests including blood tests, chest X-ray, and heart evaluation will be obtained prior to admission to the hospital for the procedure. In some situations, the patient’s internal medicine doctor or family physician may be asked to evaluate the patient for clearance for anesthesia or surgery. A restricted diet is necessary for one to two days prior to the procedure, as well as the use of an enema or cathartic to ensure that there is no retained stool in the rectum, which would inhibit clear visualization of the prostate with the transrectal ultrasound probe. During the procedure, antibiotics are administered intravenously, and at the time of discharge, a prescription for a five-day course of antibiotics will be prescribed by the urologist.
Are there any restrictions of activity following discharge after the procedure?
There are specific radiation precautions, which are minimal. The amount of radiation that can be detected outside of the prostate is very small, so an individual may conduct normal activities in public without risk of injury to other individuals. There are some restrictions regarding proximity to pregnant women and children under the age of 13 for anywhere from 2 to 6 months following the procedure.
What specific follow-up is conducted to determine whether the prostate seed implant has been effective?
At approximately 30 days after the completion of the prostate seed implant, a CT scan of the region of the prostate is obtained on an outpatient basis. The data obtained from the CT scan is important to determine the ultimate location of the radioactive seeds within the prostate. Because there is some bleeding in the prostate that occurs during the procedure, the position of the radioactive seeds may change slightly. By the time 30 days have passed following the procedure, this swelling has decreased significantly. The data obtained from the 30-day post implant CT scan is downloaded into the treatment planning notebook computer, and the radiation dose distribution is again re-evaluated. At that time, the radiation oncologist will determine whether any additional radiation treatment might be necessary in the form of external beam irradiation. Periodic follow-up examinations will be conducted at 30, 60, and 90 days, and at 3 to 6 month intervals, thereafter. After six months, the first digital rectal examination will be performed, and at each follow-up visit thereafter.
Is there is any significant risk of complications?
Serious complications are uncommon. There is a small risk of bleeding or infection. The antibiotics that are administered during and after the procedure usually eliminate any significant risk of infection. There may be some difficulty with mild discomfort with urination that may go on for several weeks to several months. Swelling of the prostate may cause some difficulty initiating the urinary stream, and medications may be prescribed to help improve the flow of urine in such situations. There is a small risk of significant damage to the bladder or rectum that could result in bleeding; however, the risk of serious bladder or rectal damage is rare. One of the most important features of the prostate seed implant is the ability to significantly spare nontarget tissues surrounding the prostate from receiving the high doses of radiation that are required to kill the prostate cancer.
How do I determine whether I may be a candidate for a prostate seed implant?
The radiation oncologists at the Carolina Radiation Medicine, Cancer Treatment Center located at 801 W. H. Smith Boulevard in Greenville, NC, have special training for the PSI procedure. At the time of the initial consult visit, a complete physical examination, review of all medical records, and blood samples will be obtained for screening for other intercurrent disease, and for determination of the prostate specific antigen level. Any additional tests or studies that may be necessary will be ordered by the radiation oncologist at that time. Subsequently, an evaluation by the urologist who will be performing the procedure with the radiation oncologist will also need to be obtained. At the time of the initial consultation, the patient will also fill out an AUA (American Urologic Association) score sheet to determine whether he is having significant difficulty with urination such that the performance of a prostate seed implant might result in an excessive risk of further difficulty with urination.
All of the above information is utilized to determine the potential use of a prostate seed implant. Consultation appointments for evaluation can be obtained by calling the Carolina Radiation Medicine, Cancer Treatment Center at 252-329-0025.
Additional information will be provided in the form of pamphlets, as
well as the viewing of videotaped information concerning various treatment
options for the management of prostate cancer, which will be made available
at the time of the initial consult with radiation oncologist.
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