John Han-Chih Chang, MD and Kenneth Blank, MD
Ultima Vez Modificado: 1 de noviembre del 2001
Dear OncoLink "Ask the Experts,"
What is Implant radiation (Brachytherapy) for prostate cancer?
Maggie Hampshire, RN, BSN, OCN with Ken Blank, MD With Special Commentary from Dr. Richard Whittington, MD, Associate Professor of Radiation Oncology Respond:
Implant radiation (Brachytherapy) for prostate cancer is the actual placement of radioactive seeds into the prostate. The advantage of this treatment over external radiation is that the radioactive seeds can deliver a highly concentrated dose of radiation to the tumor without increasing the likelihood of affecting the surrounding organs and causing side effects. Recent press coverage of this treatment option has sparked many questions. We asked Dr. Richard Whittington, Associate Professor of Radiation Oncology at The Abramson Cancer Center of the University of Pennsylvania, to answer some of the more frequently asked questions.
Can an implant be used to treat any type of prostate cancer?
Usually, implants are used only for those men with Stage B cancers.These cancers are entirely confined within the prostate capsule. If the cancer is Stage C (grown through the prostate) or greater, the implant may not work because the implant cannot reach enough tissue around the prostate.
What about my PSA (prostate specific antigen) and Gleason scorescan I have an implant if these are high?
Many authorities are not recommending implants for men with PSA levels >15 or, at some institutions, greater than 10. High PSA levels usually indicate that the cancer is beyond the reach of the radiation from implants. Similarly, Gleason scores greater than or equal to 8 indicate aggressive disease, which may have spread outside the prostate capsule. These tumors are better treated with external radiation alone or a combination of external radiation and hormones.
Are some men just too"sickly" for implants?
An implant is easily tolerated by most men. Only spinal anesthesia is needed. Men with a cardiac history or other severe medical conditions however, must be cleared medically before the procedure.
I've had a TURP - can I have implants?
Men who have already had a TURP (transuretheral prostate resection) may be at increased risk of urinary complications. According to Dr. Whittington, "It is very difficult to distribute the seeds evenly through the (prostate) gland to get an even distribution after a TURP."This may be due to scarring of the prostate tissue caused by the TURP, if this is an issue, a planning CT scan or MRI can be used to check if enough prostate tissue remains in order to have an implant.
I've been told my prostate is too large for implants. Is this true?
Men who have a very enlarged prostate prior to implantation may not be a candidate for implants. Dr. Whittington explains, "The bones get in the way of the needle and make it difficult to get the seeds out to the edge of the gland. Since most tumors arise at the outer edge of the gland, it is more likely for a piece of the tumor to be missed with the implant." For this reason it is unlikely for a man with a very enlarged prostate to be chosen as a candidate for implants, although, there is a slight possibility that these men may still be eligible for implant with hormone treatment before the implant to shrink the prostate.
The Procedure: Who does the implant?
Many centers have an "implant team" who will be present during the procedure. This team is led by a radiation oncologist and a urologist and also includes a technician, a nurse, and an anesthesiologist. The team will be wearing sterile surgical attire. They do not, however, need to wear any special radiation protection if Palladium seeds are used, because only a very slight amount of radiation is given off by these seeds and they are not, therefore, in danger from the low amount of radiation. All members of the team must be over 18 years old and not pregnant.
What happens when I enter the OR?
The anesthesiologist and assistants will administer spinal anesthesia. This will eliminate all feeling from below the waist. "General anesthesia can be used, but this requires placing a breathing tube and hooking (the patient) up to a respirator. Most patients recover more slowly from this than from spinal anesthesia." notes Dr. Whittington. You are then positioned on your back with your legs elevated in stirrups. An ultrasound probe is then placed into the rectum to show the radiation oncology physician exactly where the prostate gland is located. The entire procedure is done under continuous ultrasound guidance.
A series of hollow needles are then inserted through the skin into the prostate. When it is determined that the needles are in the correct position, the radioactive seeds are loaded through the needles. The needles are then removed and only the seeds are left behind. This distributes the seeds throughout the prostate. Dr. Whittington assures us that "After all the seeds are placed, a cystoscopy is done in case a seed falls into the bladder or the urethra. These seeds (are retrieved) and are reimplanted." When this is completed, a catheter is placed in the bladder and you are taken to the recovery room. The catheter will be removed before you go home.
How many needles and seeds are used?
This is highly variable from patient to patient and depends to a large extent on the size of the prostate gland. Larger glands need more seeds to cover the area. It is important to realize, however, "The dose (of radiation) is the same for each man." as Dr. Whittington states.
How long does the procedure take and when will I go home?
The procedure takes about 60 minutes and is done either on an outpatient basis or the patient stays one day in the hospital. At the Abramson Cancer Center of the University of Pennsylvania , the patients stay overnight.
When do the seeds come out?
The seeds will remain in the prostate permanently. They will give off more than 97% of their radiation in 6 months. The metal casings of the pellets are not reactive to the body. They are not large enough to be detected by metal detectors and do not interfere with MRI scans.
If the radioactive seeds are going to stay in me, what precautions should I take?
The radioactivity from the pellets is almost completely absorbed by the prostate. Therefore, patients are discharged from the hospital the day after the procedure without radiation precautions. However, just to be safe, most radiation oncologists recomened that children under 18 years old and pregnant women should stay 6 feet away for 2 weeks after the implant.
What are the immediate side effects and long term complications?
The side effects and complications of implant radiation are similar to those of external radiation.
Urinary symptoms are caused by the inflammation of the prostate and the part of the bladder and urethra that run through the prostate. These symptoms are frequent urination with less warning (urgency), especially at night. Symptoms usually begin one-two weeks after the implant and can last 3 months. Dr. Whittington states that "At it's worst, men go (to the bathroom) every 2-3 hours during the day and 3-4 times per night."
Some bleeding on urination may occur immediately after the implant. This is due to bruising from the needles. It will clear up in a few days. Incontinence (loss of bladder control) can occur in a very small percentage of patients. This problem may be worse when men cough or sneeze. Dr. Whittington reassures us that "this almost always clears up within 2 months".
Rectal symptoms are caused by the inflammation of the small section of the rectum, which is connected to the prostate. The symptoms are increased mucous in the stool, a feeling of irritation when passing a large bowel movement, and more frequent bowel movements. This could last 2 to 3 months. Minor rectal bleeding or ulceration can also occur. Dr. Whittington states, "Three percent of men may get an ulcer in the rectum causing pain and bleeding with bowel movements. This can happen up to 2 1/2 years after the implant and last for 4-6 months. If it is detected and treated early, the symptoms can be minimized."
Sexual function can be affected by the implants. Some men report a burning sensation on ejaculation for 3 to 6 months after implant. Some men notice a decrease in the amount of fluid on ejaculation. Patients who are considering having children after the procedure should bank their sperm before the implant. This is due to a small chance of blockage of the ducts, which deliver the sperm, and the loss of the ability to ejaculate. Forty percent of men may become impotent after the implant. Although this may seem alarming, impotency rates after implants are lower than those after external radiation or surgery.
When can I go back to work?
Patients are instructed to avoid heavy lifting for several days but can return to work the week after the implant.
How do we know if the implant is successful?
PSA levels will be closely watched over the year following implant to make sure they are decreasing. If the PSA starts to rise significantly after the implant, this might indicate either an infection or the cancer is returning. Dr. Whittington states that if an infection is suspected, "You may be treated with an antibiotic. If your PSA falls (after the antibiotics), that suggests that an infection was present. If it does not change or it goes up, that suggests that the tumor has returned." If this happens, a bone scan will be done to check for metastatic disease. If there is no bone disease, then another treatment will be considered. The possibilities include hormones, cryosurgery or experimental treatments, such as Photodynamic Therapy. The choice will depend on the extent of the cancer and the reason for the failure of the implant. All of these options should be discussed with the patient's physicians.Imprima English