Prostate HDR Brachytherapy

/Home/About Cancer/Cancer Treatment Overviews/Radiation Therapy/High-Dose Rate Brachytherapy

Prostate HDR Brachytherapy
Cancer Treatment Centers of America


Prostate cancer is the model cancer for brachytherapy. The prostate gland is located under the bladder and in front of the rectum, and it is vital that the radiation be focused in the prostate to avoid serious side effects. The prostate gland is also close enough to the skin that it can be easily reached by brachytherapy needles.

There are two major methods of prostate brachytherapy, permanent seed implantation and high dose rate (HDR) temporary brachytherapy. Permanent seed implants involve injecting approximately 100 radioactive seeds into the prostate gland. They give off their radiation at a low dose rate over several weeks or months, and then the seeds remain in the prostate gland permanently.

HDR temporary brachytherapy instead involves placing very tiny plastic catheters into the prostate gland, and then giving a series of radiation treatments through these catheters. The catheters are then easily pulled out, and no radiactive material is left in the prostate gland. A computer-controlled machine pushes a single highly radioactive iridium seed into the catheters one by one. Because the computer can control how long this single seed remains in each of the catheters, we are able to control the radiation dose in different regions of the prostate. We can give the tumor a higher dose, and we can ensure that the urine passage (urethra) and rectum will receive a lower dose. This ability to modify the dose after the needles are placed is one of the main advantages of temporary brachytherapy over permanent seed implants.


CTCA in Tulsa began doing HDR implants in January 1997. We have come to believe that there are benefits of HDR over permanent seeds.

Andy Grove (chairman of Intel) chose the HDR procedure after analyzing all the available forms of treatment, including permanent seeds. He made the analogy that this treatment was like a "smart bomb", whereas permanent seeding was a more crude "carpet bombing" treatment. He wrote about his experience in a Fortune magazine article in 1996.




What Does HDR Treatment Involve?
Our treatment frequently consists of a combination of three separate therapies:

High-dose-rate temporary brachytherapy
Moderate doses of Tomotherapy
Short term hormonal therapy (optional)
This is a three-pronged attack against the cancer, also known as "triple therapy". Sometimes we can omit the tomotherapy (external beam radiation) or hormone therapy. You may wonder why we would even want to add external beam radiation. Cancer cells may migrate outside the prostate gland, known as "extra-prostatic extension". Treatments like the radical prostatectomy and permanent seed implant alone may miss cancer cells which have escaped outside the prostate into the surrounding tissues. Scans like the CT, MRI, ultrasound, and Prostascint are far from perfect in their ability to detect cancer cell spread outside the prostate. Even though these scans may not show cancer spread beyond the prostate capsule, it can still be present. We use the external beam radiation to target those areas surrounding the prostate gland. The probability that cancer has spread beyond the prostate gland can be estimated by the Partin tables.

The HDR procedure may differ at other hospitals. At CTCA, we insert 18- 25 catheters hollow plastic needles into the prostate gland. These are placed using anesthetic, and rectal ultrasound guidance. After the needles are placed, we perform a CT scan and we do a computer plan which will calculate how long the radioactive source will stay in each needle. Three times over the following 24 hours, the needles are hooked up to the brachytherapy machine (HDR remote afterloader), and a treatment is given. During those 24 hours the patient will remain in a hospital bed.

The external beam component is given in a moderate dose, 4500 centigray divided over 4 weeks. This compares with the standard 8100 centigray divided over 9 weeks which would often be prescribed if you were having external beam radiation alone. We usually use intensity modulated radiation therapy (tomotherapy) which does its own verification that the prostate is centered in the radiation field. The reduced dose and precision targeting of IMRT may result in a lower risk of side effects. Some patients may receive broader radiation fields if there is a possibility that their lymph nodes contain cancer.

We can also offer using HDR alone without any external beam radiation for early prostate cancer. This is known as "HDR monotherapy". If HDR is given without external beam, a higher dosage must be given, over 3 - 6 treatment fractions which may require two separate implants. There is not as much experience or results using HDR monotherapy as there is with using HDR + external beam, so Dr. Flynn and Dr. Kelly believe that the combination treatment is more proven choice.

We also frequently recommend short term hormonal ablationtherapy which we start 3 months before the brachytherapy, and continue for 3 - 12 months afterwards. The hormone therapy consists of a once-every-three-month injection of Lupron or Zoladex, and an antiandrogen medication like Casodex. The hormone therapy will shrink the cancer, shrink the prostate gland, reduce the PSA, and hopefully increase the cure rate from brachytherapy because there will be less cancer cells for the brachytherapy to kill. Studies have shown that adding hormonal therapy to radiation can increase the tumor control rates, notably for Gleason 7 and higher tumors or PSA 10 or higher. Patients with an early prostate cancer may be recommended to take a shorter duration of hormone therapy, or none at all. Patients with high-risk prostate cancer may be recommended to take triple hormone blockade (Lupron + Casodex + Proscar) for approximately 15 months.


Who can have this treatment?
HDR brachytherapy program can be used for a wide range of prostate stages, PSA values, and tumor grade. The components and dosages are modified for those with low, intermediate, or high risk prostate cancer. This treatment can also certainly be used for many tumors which are considered too advanced for radical prostatectomy. As long as there is no obvious spread to distant areas of the body like the bones this treatment can be considered. For early stages, our treatment is an alternative to the radical prostatectomy, but with less side effects. Eligible patients include:
Any tumor stage (T1 - T3)

A wide range of sizes of prostate glands (large glands will require hormone therapy prior to brachytherapy)
No known spread of cancer to other parts of the body, like the bones or lymph nodes
No set PSA limit
No set Gleason limit
Previous trans-urethral resection of prostate (TURP / TUPR) is okay, but there is a higher chance of urinary control problems with any kind of treatment.
Acceptable health
Results
We have treated approximately 1000 patients with a wide range of stages. We have recently analyzed the results of our first 500 patients and these results well be sent to a medical journal for consideration of publication. We had a 5 year actuarial cancer-free rate of 97% for low-risk early prostate cancer patients. In patients with an initial PSA less than 10, and a Gleason score of 6 or less, nearly all our patients are currently free from cancer recurrence. The majority of our cancer recurrences to date have been in the bones or lymph glands in patients with aggressive high-risk prostate cancer. This is likely because the cancer had already spread in these patients by the time they were treated, but the metastases were still too small to be picked up on scans. We have a protocol in place for those patients with high-risk PCa (PSA > 20, or Gleason >= 8, or stage T3) to try to improve results over what has been achieved with other treatments in the past. We use an aggresive quadruple-modality treatment protocol.

Our side effects have been very favorable. It is typical to have urethral, bladder, and rectal irritation for a few months following the HDR and external beam. However, we have had no cases of serious long term rectal injury. The chance of requiring urinary pads because of leakage is 2.5% overall. The risk of developing impotency is approximately 35 - 40% for those treated with HDR plus external beam. This is similar to other forms of radiation or brachytherapy, but better than the risk with standard prostatectomy. If impotency develops, it can still usually be helped with Viagra or other drugs or devices. Studies show that the chance of becoming imptent is lower for those who are younger or more sexualy active before treatment.