What is External Beam Radiotherapy?
External beam radiotherapy, also known as (EBRT) is the most common form of radiotherapy.
EBRT can be given using different techniques and different types of radiation. A recommend treatment is dependent on several factors and the nature of the Prostate Cancer.
External beam radiotherapy is an effective treatment option for Prostate Cancer that is local or has not spread to other tissue or organs.
Advantages of External Beam Radiotherapy for Prostate Cancer
The advantages of External beam radiotherapy are that this treatment
- Avoids major surgery.
- Less incontinence than surgery,
- Can treat areas beyond the confines of the prostate if there is a high risk that cancer has spread outside of the prostate gland into the adjacent tissues or lymph nodes.
Types of External Beam Radiotherapy?
There are several types of External Beam Radiotherapy, some of these include:
3D Conformal Radiation Therapy
Three-dimensional conformal radiation therapy (3DCRT) is a common type of EBRT. It uses imaging scans to plan the treatment and precisely map the location of cancer within the body. The radiation is then shaped (conformed), so the cancer receives most of the radiation, and surrounding tissues receive much less.
Intensity-modulated radiation Therapy
Intensity-modulated radiation therapy (IMRT) is a highly accurate type of conformal radiation therapy. It shapes and divides multiple radiation beams into tiny beams (beamlets) that vary in strength. Volumetric modulated arc therapy and helical tomotherapy are specialised forms of Intensity-modulated radiation therapy that use a treatment machine that rotates around the body.
Image-guided Radiation Therapy
Image-guided radiation therapy (IGRT) uses a treatment machine that takes x-rays or scans at the start of each session. Markers (usually grains of gold) may be inserted into the cancer so they can be seen in the x-rays or scans. Positioning can be very finely adjusted, often to millimetre accuracy. Radiation oncologists may recommend IGRT for areas likely to be affected by movement like the prostate when the fullness of your bladder or bowel varies.
Stereotactic Body Radiation Therapy
Stereotactic body radiation therapy (SBRT) allows a few high doses of radiation to be delivered very precisely and is used to treat small cancers in the body or small metastases (cancer that has spread away from the primary cancer). Sometimes called stereotactic ablative body radiation therapy (SABR).
About External Beam Radiotherapy Treatment
Typically, External Beam Radiotherapy involves:
- Daily treatments, typically Monday to Friday
- Each treatment only lasts minutes, and
- The treatment period is usually 4 weeks
Treatment duration depends on factors like the Prostate Cancer stage and your health, and shorter protocols can also be used.
During the procedure, the patient
- sits or lies on a couch and
- an external source of ionizing radiation is pointed at a particular part of the body.
Combination EBRT With HDR Radiotherapy
In some cases, extra radiation may be required to control more aggressive cancers. In these cases, High Dose Rate (HDR) Brachytherapy can be applied for a short term delivery of the radioactive substance.
HDR cannot be performed if your prostate is too large or you have severe urinary symptoms already.
Salvage Treatments After External Beam Radiotherapy
A disadvantage with EBRT is that there are limited options available if the cancer is not totally cleared. This is because radiation damages the tissues and inhibits healing processes.
Salvage treatments after External beam radiotherapy, are limited in cases of cancer recurrence and are associated with high complication rates. Treatments that may be available could include:
Complication rates of these Salvage Treatments can be significant. It is for these reasons that radiotherapy is generally not recommended in very young men
Complications with EBRT Treatment for Prostate Cancer
Issues associated with Brachytherapy Treatment for Prostate Cancer can include:
- Impotence - Erectile function deteriorates over time at around 10% per year producing impotence rates of approximately 50% at 5 years and then deteriorates by approximately a further 5% per year thereafter.
- Stricture - there is a 5% chance that scar tissue may form in the urethra. The urethra is the tube that carries urine from the bladder through the prostate and penis. It is the tube that you pass urine through in order to urinate.
- Severe Urinary Function - approximately 5% of patients experience long-term problems with urinary urgency, frequency and bleeding
- Rectal toxicity - Up to 5% may notice an increased frequency of bowel movements and blood in the bowel motion.
- Pain with Urination (Dysuria), urinary urgency and frequency are approximately experienced by
- over 70% men at 3 months but typically resolves over time.
- up to 20% at 1 year
- 5% at 2 years
- 25% at 3 years, and
- 1% at 5 years.
- Urethral Scarring (stricture) - this produces a blockage of the urethra (water pipe that passes from the bladder through the penis) and is especially a risk in HDR where the rate is about 8%. The strictures can be dense and very difficult to treat. In these instances, the scar tissue may need to be opened with further surgery.
- Incontinence - There is a risk that you will leak urine after the procedure. This risk is approximately 2% at about 5 years
- Fistula - There is a 1% risk that you may form an abnormal connection between the bladder and the bowel, which can result in ongoing urine infections and may require further complex surgery.