What does brachytherapy for prostate cancer involve?
There are two types of brachytherapy which can be used to treat prostate cancer:
- Low Dose Rate (LDR) brachytherapy – also referred to as 'seed therapy', 'internal radiotherapy', or 'permanent seed implantation'
- High Dose Rate (HDR) brachytherapy
Low dose rate brachytherapy (seed therapy)
LDR brachytherapy is commonly used to treat low risk prostate cancer.
Tiny radioactive seeds, about the size of a grain of rice, are permanently placed inside the tumor.1 The seeds give out low levels of radiation for a few months, killing the cancer cells. LDR brachytherapy is a very effective treatment for prostate cancer.
There are three main stages to the procedure: a) planning, b) treatment delivery and c) post-procedure monitoring.
The planning stage first involves having a scan, such as an:
- Ultrasound scan;
- Computerised Tomography (CT) scan;
- Computer Axial Tomography (CAT) scan;
- Magnetic Resonance Imaging (MRI) scan.
The scan provides an accurate picture of the tumor and its position in relation to the prostate gland, as well as surrounding organs and tissues. This image helps the doctor calculate how much radiation is needed to treat the cancer and where the radiation should be placed in the prostate.
The detailed planning of the brachytherapy procedure can be ‘pre-planned’, or take place in ‘real-time’.
- Pre-planned procedure - A scan is taken the day before the treatment delivery. When completed, patients normally stay in hospital overnight and have the treatment delivery the following day.
- Real-time planning – A scan is taken immediately before the treatment delivery. An overnight stay in hospital or returning on a separate occasion is not required. Real-time planning is not available in every hospital. Patients may wish to check with their doctors whether it is available at the clinic where they are having their procedure.
To avoid discomfort, a general anesthetic or a spinal anesthetic is given before the delivery of the treatment begins.
Using the plan as a guide, the doctor will place the radioactive seeds inside or near to the tumor using a series of fine needles (also known as catheters). The needles are inserted into the skin between the scrotum and the anus to reach the prostate. The radioactive seeds are then delivered into the prostate through the needles. The needles are then carefully removed, leaving the seeds in place. Ultrasound is usually used to enable the doctor to see where the needles and seeds are being placed. This helps ensure that the treatment precisely targets the tumor.
After the seeds have been implanted, a CT or MRI scan may be taken, to make sure that the procedure went well. The whole procedure takes about one hour.
Once the seeds have been implanted, they will gradually give out radiation over the course of several months to kill the cancer cells. The level of radiation given out is very low and localized to just the prostate. It does not make the patient radioactive.
A follow-up appointment will be scheduled for about 4 to 6 weeks after the procedure. This appointment is to check that the treatment is going well and monitor for any possible side effects.
Over time, the radiation given out by the seeds will reduce to almost nothing, at which point the seeds become inactive.
High dose rate brachytherapy
HDR brachytherapy involves the temporary placement of a radioactive source to treat the cancerous tumor.1
In contrast to low dose rate brachytherapy (seed implants), no radioactive material is left in the prostate after treatment.
HDR brachytherapy has been shown to be an effective treatment for intermediate and high risk prostate cancer.2-5 It is often given in combination with external beam radiotherapy (EBRT), as it can provide an additional dose of radiotherapy to help prevent the cancer from returning.
Some centers offer HDR brachytherapy as the sole method of treatment as it is very effective and quick treatment, making it very convenient for many patients6. Your doctor will be able to advise you if HDR brachytherapy is a possible treatment option for you.
The planning for HDR brachytherapy is very similar to the planning process for LDR brachytherapy (see above).
The patient first has a scan, providing the doctor with a picture of the tumor and the prostate gland. This enables the doctor to plan how much radiation is needed to treat the cancerous tumor and where the radiation needs to be targeted.
Again, as with LDR brachytherapy the planning stage can be pre-planned (the day before treatment) or it can be planned in real-time (immediately before treatment).
Fine needles (also known as catheters) are placed into the prostate gland. A computer controlled machine sends a small radioactive source into the fine needles, one-by-one. The source travels along the needles to the prostate and they are left in place for a short period of time (seconds). The radioactive sources are then transferred back out of the prostate along the needles.
This process is repeated in a series of treatments in several sittings, usually over a 24 hour period.
The computer is programmed to control very accurately where the radiation is delivered and how long it remains in the prostate gland. This ensures that a very precise and accurate dose of radiation is delivered to the tumor. This precision reduces the risk of healthy surrounding tissues or organs being damaged by the radiation.
In high risk and intermediate risk disease a combination of External Beam Radiotherapy (EBRT) and brachytherapy may be advised by your doctor. Cure rates (measured by monitoring patients' PSA levels) have been shown to be improved when brachytherapy was added to EBRT.3,4,5
A follow-up appointment will be scheduled for approximately 4 to 6 weeks after the procedure.
This appointment is to check that the treatment is going well and monitor for any possible side effects.
1. Holloway C, Hsu I-C, Albert M, et al. In: Brachytherapy: Application and techniques. Devlin PM (Ed). Philadelphia, PA, LWW. 2002.
2. Fatyga M, Williamson JF, Dogan N, et al. Med Phys 2009;36(9):3995-4006.
3. Hoskin P, et al Radiotherapy and Oncology 103 (2012) 217–222.
4. Deutsch I, et al. Brachytherapy 9 (2010) 313e318
5. Grimm P. et al. BJU Int 2012 ;109 (Suppl 1): 22-29
6. Helou J. et al. Radiotherapy and Oncology 115 (2015) 84–89