Brachytherapy,
or prostate seed
implantation, is a type of radiation therapy in which
radioactive metallic
seeds smaller than a grain of rice
are permanently placed
inside the prostate gland. This
therapy delivers a high dose of radiation directly
to the prostate gland and sometimes to the seminal vesicles.
The seeds
give off their radiation slowly over several months and within
one year, their radiation completely decays. The seeds can
remain safely in place for the rest
of a man’s life.
While brachytherapy has shown some promising early results, the long-term effectiveness of this therapy is not yet known. In a 1997 study of men with stage T1 or T2 prostate cancer who had received brachytherapy, the 7-year actuarial (statistically estimated) disease-free survival rate, with PSA values of 0.5 or less, was 79 percent¹. Publication of the results of longer-term, 10-year studies, are expected in the near future.
This
section discusses methods of treatment
delivery, seeds used in brachytherapy,
treatment planning; what to expect
before, during
and after implant surgery; follow-up
testing; advantages and disadvantages
of brachytherapy; treatment side effects;
and high-dose rate brachytherapy.
Methods of treatment delivery
Depending on the stage of the cancer, brachytherapy can be given in the following ways.
Two types of seeds are typically used:
The
number of seeds needed for treatment is determined by the
size of the prostate gland and the dose of radiation being
used. Typically, between 70 and 150 seeds are placed at one
time.
Prior to implant surgery, you will need to have a transrectal ultrasound, a 5- to 15-minute outpatient procedure that uses sound waves to create a video image of the prostate gland. This allows the doctor to measure the size of the prostate, plan for the implantation and place the seed order.
Two weeks before surgery, you will have routine blood work, an electrocardiogram (EKG) and a chest x-ray. You may be instructed to stop taking aspirin and nonsteroidal anti-inflammatory drugs to minimize the risk of bleeding during and after surgery. If you take blood thinners, you may need to stop taking them or have the dosage adjusted by your doctor.
The day before surgery, your doctor may put you on a liquid diet and have you take laxatives and an enema or suppository. This is necessary to clean the rectum for the transrectal ultrasound. Do not eat or drink anything after midnight right before the implant.
Prostate seed implantation can be performed with either spinal anesthesia or general anesthesia. The day of surgery, an intravenous (IV) line will be started in your arm to supply you with medications during the procedure. You will be given enemas to clean the rectum. A catheter will be placed through the penis and into the bladder to drain urine.
A urologist and radiation oncologist work together to perform the implant. The urologist is responsible for the transrectal ultrasound and places a probe in your rectum to locate the prostate gland so it can be viewed on a monitor. A plastic template with tiny holes is placed against the perineum (the area between scrotum and anus). The radiation oncologist places thin, hollow needles through the grid and perineum and into the prostate gland. The radioactive seeds are put through the needles and planted in the prostate about 1 centimeter (a little less than ½ inch) apart. The entire procedure lasts about 90 minutes.
The catheter may be left in place for a few days until prostate swelling subsides. Most patients are discharged three to four hours after the implant procedure.
There is little discomfort after the implant, except for some mild soreness in the perineal area lasting for one to two days. Sometimes some mild rectal bleeding or spotting will occur for about 24 hours in the area in which the needles were inserted. There may be a small amount of blood in the urine. This is normal and should stop in one to two days. Your doctor may instruct you to use an antibiotic cream on the surgical site for a few days following surgery.
For the first two days after surgery, avoid heavy lifting or hard physical activity. After that, you may return to your normal activity level.
Safety Precautions after Surgery
A follow-up appointment will occur six to eight weeks after surgery. It will include x-rays and a CT scan of the pelvis to indicate the positioning of the seeds and help determine the dose of radiation the prostate is receiving.
A digital rectal examination (DRE) and prostate-specific antigen (PSA) blood test will be given every three to six months during the two years after treatment. After radiation treatment, PSA levels take between 18 and 24 months to reach their lowest point. (In contrast, after radical prostatectomy, PSA levels drop to their lowest point immediately after surgery.) In the 24-month period after radiation therapy, PSA levels may bounce up and down from reading to reading. This fluctuation is normal and not a cause for concern unless three consecutive readings indicate a consistently rising PSA.
Unlike major surgery or daily radiation treatments, brachytherapy causes little interruption in your daily activities. In addition, this treatment usually preserves continence and causes erectile dysfunction less frequently than surgery or external beam radiation therapy.
Disadvantages of Brachytherapy
Disadvantages, such as infection and bleeding, are those of a 90-minute surgical procedure. Death is a risk of all surgery involving general anesthesia, but is an extremely rare occurrence with this procedure.
The following side effects are generally caused by the radiation emitted by the seeds in the prostate. The effects may last for two to 12 months after the implant and will decrease gradually as the seeds lose their radioactivity.
High-dose rate brachytherapy is the placement of highly radioactive material inside the prostate for less than one day. It delivers a concentrated dose of radioactivity to the tumor. Careful needle placement will prevent radiation damage to the rectal wall. For about a week following the procedure, patients may experience perineal pain and their urine may be red-brown.
1 Ragde H, Balsko JC, Grimm PD, et al. Interstitial iodine-125 radiation without adjuvant therapy in the treatment of clinically localized prostate carcinoma. Cancer 1997;80:442-453.
The Prostate Cancer pages of this Web site are part of the Comprehensive Prostate Cancer Awareness Program (CPCAP), a major regional effort to reduce the rates of death and illness caused by prostate cancer in southwestern Pennsylvania. Funding for CPCAP is provided by a grant from the Commonwealth of Pennsylvania.
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