Brachytherapy Treatment

Treatment Options: Brachytherapy

Prostate brachytherapy is becoming an increasingly popular treatment for localised prostate cancer. The application of brachytherapy techniques allows the safe delivery of higher doses of radiation than those that can be delivered by a conventional external beam approach. Dose escalation is now an important component of radiation medicine in the treatment of prostate cancer. In the United States, the use of brachytherapy is now almost as common as radical prostatectomy.

Brachytherapy is either applied as low dose rate (LDR) permanent implants or high dose rate (HDR) temporary implants. LDR Brachytherapy, also known as seed implants, is typically used as a stand alone treatment for low risk prostate cancer. HDR Brachytherapy is usually employed in conjunction with external beam radiation where the tumour characteristics suggest an intermediate or high risk prostate cancer.

Prostate brachytherapy has become an increasingly popular treatment for localised prostate cancer. The application of brachytherapy techniques allows the safe delivery of higher doses of radiation than those that can be delivered by a conventional external beam approach.  Dose escalation is now an important component of radiation medicine in the treatment of prostate cancer.  In the United States, the use of brachytherapy is now almost as common as radical prostatectomy.

Brachytherapy is either applied as low dose rate (LDR) permanent implants or high dose rate (HDR) temporary implants. LDR Brachytherapy, also known as seed implants, is typically used as a stand alone treatment for low risk prostate cancer. HDR Brachytherapy is usually employed in conjunction with external beam radiation where the tumour characteristics suggest an intermediate or high risk prostate cancer.

  • Brachytherapy – Low Dose Rate
  • Bracytherapy – High Dose Rate

Brachytherapy – Low Dose rate

What is a prostate implant?

This is a procedure in which tiny radioactive seeds are inserted into your prostate. These seeds contain radioactive iodine or palladium within a thin metal case. Each seed is less than 5mm in length and less than 1 mm in thickness.

The radioactive iodine gives off low energy radiation that is absorbed almost entirely within the prostate itself. The implant is tailored to the shape and size of your prostate, and typically 90 to 120 seeds are used. The seeds deliver a field of radiation at high doses which is largely limited to the prostate. This field of radiation is capable of killing the prostate cancer cells.

The radioactive iodine “decays” over several months. During this time, the radiation treatment is administered to the prostate. The amount of radioactivity decreases by 50% every 60 days.

By 6 months about 85% of the radiation has been given, and it is almost entirely gone by one year. The inactive metal seeds then remain within the prostate permanently.

Is the treatment effective?

Long-term data from two centres of excellence, Seattle and New York, is now available and clearly demonstrates that LDR Brachytherapy is a safe and effective treatment for patients with low-risk prostate cancer. The likelihood of cancer cure is the same as that seen in patients who undergo a radical prostatectomy. Other treatment centres have demonstrated that these excellent results can be matched with appropriate training in the brachytherapy technique.

Low risk prostate cancer is defined as a PSA <10ng/ml at the time of diagnosis, a Gleason score of < 8 and a clinical stage of cT2b or less. At present, there is only a Medicare rebate available for this treatment if the prostate cancer meets these criteria.

There is evidence becoming increasingly available that LDR Brachytherapy is also an effective treatment for some patients with intermediate risk disease. At present, there is no Medicare rebate available for this group of patients.

Planning the Implant

Most patients will have had their prostate cancer diagnosed on a trans-rectal ultrasound and needle biopsy of the prostate. They may have also had a CT scan and/or bone scan to confirm that the cancer is localised to the prostate.

Prior to undergoing a seed implant, another specialised test must be performed. This is called a Volume Study. This is usually done by a urologist or radiation oncologist and involves a day stay visit to the hospital.

A trans-rectal ultrasound (TRUS) is performed to accurately map out the size and position of the prostate. There may be some temporary burning when passing urine after this procedure.

The information obtained at the Volume Study is then used by the radiation oncologist, urologist, medical physicist and radiation therapist, aided by sophisticated computers, to determine the number, strength and location of seeds required to treat the cancer – the treatment plan.

The Implant

Patients are admitted to hospital the day of surgery.  A bowel preparation kit is provided and there is a regime of medications which are required in the lead up to the implant procedure.

The seeds are implanted using long thin needles that are inserted into the prostate through the skin behind the scrotum.  An ultrasound probe in the rectum and an X-Ray monitor are used to guide the needles. The number of needles and seeds required varies from patient to patient depending on the size and shape of the prostate gland. When each needle is in its correct position in the prostate, the needle is slowly withdrawn while individual seeds are injected into the prostate gland. Both the probe and the needles are removed when the procedure is completed.

The radioactive seed implant procedure usually takes under an hour to perform. After the seeds have been implanted, the urologist may perform a cystoscopy to remove any loose seeds.  A catheter will be left in the bladder temporarily to drain urine.  The implant procedure usually involves an overnight stay in hospital, though in some circumstances patients may be discharged the same day.

Approximately 4 weeks later a CT scan of the pelvis is performed to assess the position of the seeds and to determine the quality of the implant.

This step is an important part of the procedure and is similar to a surgeon assessing the pathology after an operation. It is rare for extra treatment to be required after a seed implant.

What are the side effects?

  • Slight bleeding, bruising and tenderness between the legs
  • Burning on urination, urinating more frequently, mild pain or a feeling of restricted urination are common. These symptoms typically resolve over the first few months and are treated with Flomax in the short term.
  • Rectal discomfort is uncommon.  Constipation should be avoided if possible.
  • Your first ejaculations may be uncomfortable and blood stained. Rarely, discomfort with ejaculation may persist beyond the first few months.
  • In a small percentage of patients (less than 10%) complete blockage of urination may occur, and a catheter is required in the short term.

Most of these side effects can be controlled with changes in the schedule of medications.

Later side effects include:

  • A small risk of developing a urinary stricture or narrowing of the urethra that may make it difficult to pass urine. This can usually be treated a urologist.
  • A small risk of ongoing urinary symptoms. These may include burning, frequency, urgency and rarely urge incontinence.  These symptoms are usually controlled with medications.
  • Erectile dysfunction is very variable. The most significant factor is the quality of erections prior to the treatment.  If normal erections were present before treatment then it is likely the erectile function after the treatment will be good.  Patients who do develop erectile dysfunction following treatment often respond to medical therapies, such as the Viagra class of drugs.
  • There is a small risk of causing an area of ulceration of the rectum.
  • Fertility is unlikely to be affected with seed brachytherapy

What about follow-up?

A CT scan is performed 30 days after the implant. This is used to determine the dose of radiation received by the prostate, and ensure that the dose delivered is sufficient to kill the cancer cells. Follow-up visits with your urologist and radiation oncologist will be performed on a regular basis. At each visit, you will be asked to fill out a questionnaire asking you to comment about side-effects and quality of life. A PSA will usually be performed prior to these visits

Is the radiation dangerous to me or my family?

Iodine-125 emits very low-energy radiation which does not travel far.  The majority of the radiation is stopped inside the prostate itself.  A very small amount of radiation does escape from the body, but it is so small that it is not considered a risk for other people.  It is recommended that babies and young children do not sit on the laps of people who have undergone an implant for a period of 2 months.  There is no risk of the radiation harming other people through normal activities such as living together, sleeping in the same bed or even through sexual intercourse.

Although it is rare, an occasional seed may be lost via urination. If a seed is passed in this way, it almost always occurs within the first few weeks following the implant procedure. If a seed is passed, it should be retrieved and returned to the St George Cancer Centre for proper disposal. Because of possible passage of a seed, we ask you to strain your urine for the first week following the procedure so that any seed that is passed may be easily retrieved. The seed should then be picked up with a cotton swab or tweezers and placed in the lead lined container which will be provided.

A seed may rarely be passed in the semen. For this reason, we ask that you use a condom during intercourse for the first two months. Although these precautions may seem elaborate, the amount of radiation exposure to the patient and those around him is really quite minimal and do not represent an additional risk.

The loss of a seed or seeds in the urine or semen will not adversely affect the cancer treatment, as many seeds are used during the implant and the treatment plan has built in flexibility to allow for this possibility.

A CT scan is performed 30 days after the implant. This is used to determine the dose of radiation received by the prostate, and ensure that the dose delivered is sufficient to kill the cancer cells. Follow-up visits with your urologist and radiation oncologist will be performed on a regular basis. At each visit, you will be asked to fill out a questionnaire asking you to comment about side-effects and quality of life. A PSA will usually be performed prior to these visits

Brachytherapy – High Dose Rate

High Dose Rate (HDR) brachytherapy is a form of internal radiation therapy which is used in combination with external beam radiotherapy. It is typically used to treat intermediate and high risk prostate cancers.

At this point in time HDR Brachytherapy is used in combination with external beam radiotherapy, and not as a stand alone treatment like seed brachytherapy.

The treatment is delivered through the use of small plastic catheters inserted directly into the prostate gland.  These plastic catheters act as a conduit allowing a radiation source to be placed within the prostate. A number of radiation treatments can then be delivered through these catheters. Once the radiation has been delivered the catheters are removed and no radioactive material is left within the prostate gland. A computer controlled device, called a Remote Afterloader, moves a radioactive iridium source, located on the end of a wire, into each of the catheters. The radioactive iridium source is then positioned at a number of “dwell” positions to deliver the radiation dose within the prostate. These positions are determined with the aid of a planning computer allowing optimal dose of radiation to the prostate. The treatment is tailored to deliver an optimal dose to the prostate and to minimise the dose to other structures, including the urethra and the rectum. The ability to alter the dose after the plastic catheters have been inserted into the prostate is one of the major advantages of HDR brachytherapy.

HDR brachytherapy involves a treatment program, which comprises three separate stages:

  • Short or long term hormonal therapy;
  • High Dose Rate brachytherapy and
  • A moderate dose of external beam radiation

This treatment approach aims at optimising cancer control within various regions. The hormonal therapy acts systemically as well enhancing the effects of the radiation within the prostate. External beam radiation is used to treat potential prostate cancer that has spread beyond the capsule of the prostate and in the surrounding tissues and lymph glands. The HDR component of the treatment aims at maximising the dose of the radiation, or dose-escalating, where there is the highest likelihood of cancer, that is, within the prostate.

Implant Procedure

Typically the patient is admitted the day of the surgery. A bowel preparation kit is provided and there is a regime of medications to be taken in the lead up to the HDR implant.

The HDR implant involves a short procedure in the operating theatre where small hollow plastic needles (HDR catheters) are placed into the prostate through the skin between the scrotum and the rectum.

X-rays and ultrasound imaging ensure that the needles are placed into the optimal position. This procedure is done under a general anaesthetic or spinal anaesthesia.

The patient is then transferred to a CT scan where imaging of the prostate and catheters is undertaken. Computer planning allows accurate calculation of the dose to be delivered and adjustment of the radioactive source positions within the prostate. Once the plan has been completed, the radioactive iridium source is delivered to the prostate.  Three separate treatments are then delivered over 36 hours.

The period of hospitalisation is typically 2 days. The needle placement is performed in the morning, a CT scan is performed by midday and the planning is completed in the early afternoon. The first treatment of HDR is delivered late in the afternoon of the first day. The following day a treatment is delivered in the morning and again in the afternoon. Once the treatment has been delivered the catheters can be removed and patient discharged the following morning. During the 2 days the patient is confined to bed and significant movement, such as sitting up or walking, is not possible. A urinary catheter is inserted during the initial procedure and removed at the end of the brachytherapy treatment.

External Beam Radiation

Approximately 2-3 weeks after the completion of the HDR Brachytherapy a course of external beam radiation treatment is delivered. This is at a moderate dose (46Gy in 23 separate treatment sessions) over 4-5 weeks.  Each session is given as an outpatient and usually takes 20-30 minutes. A planning session, or simulation, will be required to plan this part of your treatment. The extent of the radiation field is determined primarily by the potential risk of the cancer for spread beyond the capsule of the prostate and to the lymph glands.

Hormonal Therapy

Hormonal therapy is usually commenced at least 3 months prior to the HDR Brachytherapy and continued for a short interval afterwards. Patients with high risk disease may continue with hormonal therapy for longer periods after the HDR Brachytherapy. This will be discussed by a radiation oncologist or urologist.

Side Effects

Slight bleeding and bruising and tenderness between the legs are common. Burning on urination, urinating more frequently, or a feeling of being unable to pass urine freely are possible side effects.

Rectal discomfort is uncommon with respect to the HDR component of the treatment. Towards the end of the external beam radiation treatment some patients may experience temporary diarrhoea. Long term complications from the external beam radiotherapy are uncommon due to the moderate dose which is used. Urinary incontinence is very rare.

The risk of developing impotence is thought to be approximately 30-40%. This is similar to other forms of radiation or brachytherapy. Long term results are not yet available. If impotence occurs it can usually be treated with the use of tablets such as Viagra, or other medications or procedures.