Prostate brachytherapy, a technique of placing multiple, tiny radioactive seeds into the prostate gland, has been one of the more promising recent improvements in prostate cancer therapy. These radioactive seeds are needle-placed directly within and adjacent to the prostate tumor, and they deliver a higher dose of radiation to the tumor than does the external beam technique.
This same-day-surgery technique uses fluoroscopic and biplanar-ultrasound guidance to enable the most-accurate interactive positioning of the insertion needles and the precise placement of an evenly spread 3D-grid of the radioactive seeds throughout the prostate gland.
Dr. Gordon Grado had originally developed this treatment as an option for locally recurrent prostate cancer, to be used for local tumor recurrence following previous surgery or radiation therapy. Because of his success with locally recurrent cancers, however, this approach and technique were expanded to include early stage or locally advanced prostate cancer.
We are now able to treat patients with all sizes and shapes of prostate glands, including those patients with enlarged glands or those who have previously undergone prostate surgeries such as a TURP procedure (transurethral resection of the prostate) for obstructive urinary symptoms.
Iodine-125 or Palladium-103 are the radioactive isotopes contained within these implantable seeds. These radioactive sources are placed into the prostate gland via pre-loaded needles or by using a specialized insertion “gun.” These isotopes release all their irradiation energy within a few months of being implanted. Because of the low energy of the x-rays released from these isotopes, radiation dose is deposited within millimeters of the seeds’ positions. Dose delivered to adjacent normal organs is minimal.
As only a small volume of prostate tissue is irradiated by each seed, many seeds must be evenly positioned throughout the prostate tissue to cover the entire prostate and the cancer site within the gland. The entire prostate gland is treated, because microscopic cancer cells may be present at multiple sites within the gland, even though the biopsy may have been positive in only one location. The number of seeds required for treatment depends on the size and shape of the prostate gland, as well as the activity strength of the seeds. On average, approximately 100 seeds may be implanted through 18 or so needles.
Before the procedure, the patient is carefully evaluated to make sure he is an appropriate candidate for prostate brachytherapy, which is defined by several staging tests.
Clinical History & Physical Exam
All patients will have a detailed clinical history obtained as it relates to their general health, prostate cancer diagnosis, previous surgery or radiation treatment. This will be followed by a complete physical exam and detailed digital rectal exam.
Prior to the implant procedure, blood work, an electrocardiogram (EKG) and a chest x-ray are done. These tests aid the anesthesiologist in determining the patient’s ability to receive anesthesia. Either a spinal or general anesthesia will be given.
Prostate Ultrasound Volume Study
A specialized ultrasound exam of the prostate gland determines the prostate’s volume and whether the prostate capsule remains intact, thereby verifying that the cancer is in an early stage within the prostate. From these images, we can calculate the number and position of the needles and radioactive sources that are required to be placed throughout the prostate gland. If the prostate gland is determined too large for the template (>6 cm wide), hormonal downsizing may be required. Ultrasound staging and evaluation of the site’s neurovascular bundles will be performed.
CT Scan of the Pelvis
This high-resolution x-ray study of the pelvis is utilized to look for any pelvic lymph node enlargement or other evidence of cancer presence outside of the prostate region. The relationship of the prostate to other normal structures in the pelvis is identified, as well as its association to bony anatomy. Contraindications for the prostate seed implant may be detected by this x-ray exam.
Preparing for the Prostate Seed Implant
It is important to review with the physician all of the medications being taken, as some drugs, such as “blood thinner” medication, could adversely affect the procedure or cause an unnecessary delay in performing the procedure.
Any aspirin product or non-steroid anti-inflammatory medication should be discontinued seven days prior to the implant. The day before the implant, a special diet and bowel prep will be started. This prep will remove fecal material from the lower bowel and rectum that could interfere with the ability to obtain a clear ultrasound image of the prostate at the time of surgery. The patient should not eat or drink anything after midnight the day before the procedure. Any prescription medications may be taken with a small sip of water. If you have diabetes, you will want to check with your doctor before taking medications that lower your blood sugar.
Prostate Seed Implant
The procedure is done in a sterile operating room as an outpatient. The patient will be asked to report 1-2 hours prior to the procedure for registration and preparation. The entire procedure lasts approximately one hour. After the patient is precisely positioned on the operating room table, an individual specializing in prostate ultrasound will place the biplanar ultrasound probe into the rectum to image the prostate. The ultrasound probe is carefully held in position by a stabilizing device that is attached to the O.R. table. Biplanar, transrectal ultrasound, along with fluoroscopy, gives a multi-dimensional view of the prostate gland on several video screens in the O.R. These images obtained are used to place the needles and space the radioactive sources accurately within the prostate gland. The implant procedure does not require a surgical incision.
Needles are advanced through an area of skin called the perineum (behind the scrotum and in front of the rectum) into the prostate, with the aid of a template attached to the ultrasound probe and a computer plan designed specifically for the patient’s prostate gland size. Radioactive seeds are then deposited through the needle into the prostate gland, based on a precise map that was planned before going to the O.R. and then re-checked and modified at the time of surgery. The dose needed is calculated by pre-implant dosimetry from the volume study. The seeds are permanently placed in the prostate gland and give off the radiation over the seed’s life span of 3 months to a year (depending on the radioactive seed that is selected). Both the probe and needles are removed when the procedure is completed, and a Foley catheter is left in the bladder until the patient recovers. Cystoscopy at the completion of the procedure is rarely needed, except to evaluate the urethra and the bladder if necessary. The patient will then be transferred to the post-anesthetic care unit for an hour or more of recovery, where the patient will wake up and receive discharge instructions. Once recovered, he will be discharged.
When the catheter is removed, the patient will be taught intermittent self-catheterization, should he have any voiding difficulty. Most patients, however, do not have to catheterize themselves. The patient’s urine may contain a small amount of blood for a short period of time. This is nothing to be alarmed about and should subside in 24-48 hours.
A CT scan of the prostate and PSA level check will be done prior to discharge. The CT scan and postoperative films will be utilized for evaluation of seed placement and to calculate the total dose delivered. Later in the day or in the morning following the procedure, the patient will have a post-op visit.
Discharge instructions will be provided. Antibiotics will be given for five days following the procedure. If necessary, prescriptions for pain medications will be provided. Heavy lifting or strenuous activity should be avoided for 30 days after the procedure, but walking, swimming and golfing are fine. After that, the patient may return to a normal level of activity. Follow-up appointment will be scheduled in 2 to 3 months, which will consist of a PSA blood test, a physical exam including a digital rectal exam, and an x-ray study of the seeds within the prostate gland, or ultrasound if necessary.
Iodine-125 and Palladium-103 are low energy, radioactive materials. This means that the radiation travels only a short distance, with the majority of radiation effects delivered within the prostate area, “shielded” by the surrounding body tissues. Exposure to family and friends is minimal, and special precautions are not indicated, unless otherwise advised by the doctor or nurse.
Short-Term Side Effects
Some patients experience burning or discomfort with urination that may last from a few days to several weeks. Patients may also experience some increased frequency and urgency with urination. These symptoms are due to swelling in the prostate that results from the placement of needles during surgery. Medications are available to decrease these side effects. When the swelling subsides, so do the side effects. In our experience, most of the side effects are gone within a few months.
Long-Term Side Effects
After receiving radiation to the prostate gland, any anticipated future surgeries to this region of the body should be first discussed with the Radiation Oncologist who had been involved in the brachytherapy placement.
Procedures that require caution include colonoscopy, proctoscopy, sigmoidoscopy, and cystoscopy. Most delayed, long-term side effects can be avoided by following careful instructions from their brachytherapy physician. The observed rate of impotency is small, and the rate of urinary incontinence is negligible, unless a previous surgical procedure to the prostate or transurethral resection of the prostate had been performed or if hormonal deprivation were utilized.
With the techniques and equipment we now have available, radioactive sources can be very carefully positioned throughout the prostate gland and the prescribed treatment delivered. We have developed specialized brachytherapy techniques for patients having undergone a TURP (transurethral resection of the prostate), had previous radiation to the prostate area, or have enlarged prostate glands. Radioactive sources can be positioned to deliver tumor-killing radiation doses, accounting for previous radiation delivered for prostate cancer or for other malignancies.
Prostate gland size may present some problems, which can be accommodated. Gland sizes treated with this technique have ranged from 8 to 210 cc (cubic centimeters). Equipment development and expertise has allowed us to specialize in these more difficult patient problems.
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