External beam radiotherapy for prostate cancer (EBRT) means that high energy X-rays are used to treat prostate cancer.
A special machine called a linear accelerator produces high energy x-ray beams which are then very carefully and accurately aimed at the prostate. The treatment can also cover a small area around the prostate, including the seminal vesicles, in case the cancer has spread to these areas.
As all the organs inside the body lie quite close to each other, the beam is shaped to fit your anatomy and surrounding areas of prostate, bladder, back passage and hips. The beam is shaped by the use of multi-leaf collimators within the head of the linear accelerator. By shaping the beam the prostate can be accurately targeted and reduce the dose to the healthy surrounding normal tissues of the bladder and bowel. These beams kill the cancer cells inside the prostate.
Why might EBRT be suggested?
EBRT can be used in the following ways:
- As the primary/main treatment when the cancer is localised, contained within the prostate and has not spread (metastasised) to other parts of the body – -this is called radical radiotherapy;
- For men with low, intermediate and high-risk prostate cancer. (For further information about the risk categories of prostate cancer please page 32 of the Early prostate cancer explained booklet)
- As a treatment, after a period of active surveillance. If there are signs of the cancer growing or progressing, then EBRT may be one of the treatment options offered to you;
- For men who are expected to live for at least 10 years;
- After radical prostatectomy (surgery to remove the prostate) if there are high-risk features or if there are signs of the cancer growing again (shown by rising PSA after surgery);
- For men who are fit enough to have treatment and do not have other significant medical conditions that may impact on survival and life expectancy;
- In combination with hormone therapy for treatment of cancers that have spread out-with the prostate capsule or affected other organs nearby such as the seminal vesicle. Hormone treatment can be used on a short term basis (3-6 months) or long term basis (2-3 years);
- Smaller doses of EBRT can also be used very effectively to treat bone pain in cases of cancer spread to the bones.
Why might hormone therapy be given before or after EBRT?
Prostate cancer grows in response to the male hormone testosterone. Hormone treatment (or therapy) works by reducing the amount of testosterone in your body and as a result slows down the growth of the cancer or shrinks it. However, hormone treatment does not cure prostate cancer.
Some men may be given hormone treatment for prostate cancer for several months before radiotherapy treatment with the aim of shrinking the cancer so that radiotherapy has a higher/better chance of working.
For men who have high-risk prostate cancer hormone therapy may be continued after radiotherapy. In this case radiotherapy usually starts after 3 – 6 months of hormone therapy and only when the PSA level is less than 1. Hormone therapy is continued for up to 2-3 years as it has been shown to reduce recurrence rates and improve survival.
What happens with EBRT
Every man who has decided on EBRT as his treatment will have an individual plan of care so he will be told when and how many treatments (these treatments are called fractions) he is likely to have.
Although there may be variations in the treatment centre attended, it is usually in the region of between 19 to 40 treatments carried out over 4 to 8 weeks. Although for radical radiotherapy to the prostate, it’s now becoming more common for men with low or intermediate-risk prostate cancer to be given higher doses over a shorter period often 20 days;
This means that each day a daily dose of radiation, called a fraction will be given. By breaking up the treatment like this, normal tissue which might be affected by the treatment has time to recover between treatments, but the cancer cells don’t recover so easily. As each dose of radiation causes a little more damage to the cancer cells, it’s important to attend all the appointments as planned.
The planning stage
Before starting radiotherapy, your treatments need to be planned carefully and this may take a few weeks. It is to find out the exact position of your prostate and to make sure that the same area is treated each time.
In some centres, 3 small gold marker (fiducial) seeds/markers may be inserted into the prostate prior to or just before the planning scan (this is done in similar way to having a TRUS biopsy). If the hospital uses these markers then these are generally implanted into your prostate at least 7-10 days before your CT scan, so they have a chance to settle into place.
These seeds/markers are not radioactive but are used to ensure that the radiotherapy beams are very accurately targeted at the prostate and minimise the dose to the bowel and bladder.
CT (Computerised Tomography) Planning Scan
Before starting radiotherapy treatments, an appointment will be given for a special CT scan; this is the first stage in planning your radiotherapy treatment.
The CT scanner is a special type of x-ray machine that is used to take many detailed pictures of different views inside your body. The appointment for the CT scan usually takes about 30 – 45 minutes.
At this scan you will lie on your back on the scanner bed and the radiographers will get you into the correct position sometimes using rests and supports to get you into an exact position now and for all your future radiotherapy treatments.
To make sure the same area is treated every time, the radiographer will make a number of pinpoint dots (about the size of a freckle) on your skin. So these tiny marks don’t wash off, they will be ‘tattooed’ onto your skin. These dots or tattoos don’t show where you need treatment or show where the tumour(s) are they’re just to make sure you lie in the correct position. The bed will move through the scanner and special pictures are taken of the pelvic area.
The CT scan is downloaded into a special computer and the oncologist (doctor treating the cancer) will identify the area to be treated. Because of all the planning involved radiotherapy treatment will not start straight away and it may take around 2 weeks before treatment starts.
The treatment is different for everyone. Usually radiotherapy treatments will be given every day, Monday to Friday, for between 4-8 weeks as an outpatient. For radical radiotherapy to the prostate, it is now becoming more common for men with low or intermediate-risk to be given higher doses over a shorter period, often 20 days.
Each day a daily dose of radiation, called a fraction will be given. By breaking up the treatment like this, normal tissue which might be affected has time to recover between treatments, but the cancer cells don’t recover so easily. As each dose of radiation causes a little more damage to the cancer cells, it is important to attend all the appointments as planned.
Before the CT scan and radiotherapy appointments, suppositories/enemas may be given which are used to get rid of wind or gas in the bowel. As the use of enemas varies in different hospitals, the CNS, radiographer or oncologist will advise if, when and how many enemas might be given.
As with the CT scan, radiographers will ask you to lie down on the bed and will make sure that you are in the correct position, perhaps using rests and supports. Once everything is ready, the radiographer will go into another room and turn on the machine. Although you will be on your own, the radiographer will still be able to see you and talk to you;
There will be a ticking noise as the machine moves around, perhaps into three or four different positions. It’s important to lie very still but still breathing normally. While the appointment might last for up to an hour, the treatment only lasts about 10-15 minutes with the machine only being on for about 5 minutes. The rest of the time is taken in making sure that you are in the correct position so the cancerous cells in the prostate can be accurately targeted.
This treatment doesn’t make you radioactive, so it’s safe to go home and be with other people.
Will I have an anaesthetic?
No. The treatment is like having an x-ray. You can’t see the radiation and it doesn’t feel hot or cold and shouldn’t cause any pain.
Potential short-term side effects
Feeling tired and having little energy
During radiotherapy your body uses a lot of energy dealing with the effects of radiation on normal cells. Most people will be able to carry on with their usual daily activities and some people carry on working. Feelings of tiredness can build up over the course of treatments but should go away gradually when the treatment finishes.
Symptoms when passing urine
Because the bladder lies close to the prostate it may become irritated or inflamed because of the treatment you may notice that you need to pass urine more often during the day and during the night, you need to pass urine more urgently and that you have a burning feeling when passing urine.
Because the bowel lies close to the prostate and may become irritated or inflamed because of the treatment you may notice that you need to open your bowels more often and motions may be looser with a feeling of urgency to open your bowels. You might have cramps in your lower tummy and pass a lot of wind. If you see blood in your motions, it’s important to let the oncologist or CNS know.
Proctitis is an inflammation of the lining of the rectum and may be troublesome towards the end of and for 4-6 weeks after your treatment has finished. You may notice a frequent or continuous feeling that you need to have a bowel movement, some bleeding from your bottom and pain, diarrhoea and pain with bowel movements.
You may find that the skin between your legs will briefly become red and sore, a bit like sunburn. Ask the doctor what can be done for this.
You will lose hair in the area of treatment and this may not grow back, but it will not cause you to lose the hair on your head.
Most side-effects will settle down after your treatment has finished. For some men the side-effects can be more lasting.
Some men find that their bowel habits will change permanently. It might be small changes like opening your bowels more often during the day, having a slightly looser bowel motion or passing more wind. If bowel habits are having a big effect on your life it’s important to let the CNS or oncologist know, especially if there is bleeding from the back passage.
Symptoms when passing urine
Passing urine more often or having difficulty in passing urine may be a problem but EBRT is less likely to have long-term urinary incontinence compared with having your prostate removed with surgery There are often ways to help with this difficulty if you inform your oncologist or CNS.
Difficulties with erections (erectile dysfunction or ED)
Difficulties in getting and keeping erections may occur in approximately 60% of men after radiotherapy. This is because the blood vessels and nerves needed to get an erection lie very close to the prostate and can be damaged during the treatment. You may not notice this at first, as it happens gradually and can take up to 2 years before it becomes fully apparent.
There are several types of treatment available for ED, and, if this becomes a difficulty you should speak with your CNS or oncologist. Options might include medication taken as a tablet, medication as a pellet using an applicator, cream, medication which is injected, or through the use of a vacuum pump.
Some men find that there is a reduction or in the amount of fluid when they ejaculate while others don’t produce any fluid at all, called a ‘dry orgasm.’ For further information about erectile dysfunction see the booklet Prostate conditions and erectile dysfunction
For further information about potential side effects of radiotherapy see the booklet External Beam Radiotherapy for Prostate Cancer
How do I know if the EBRT treatment has worked?
The PSA level will be measured and is a good indicator of whether treatment has been successful. After radiotherapy, PSA will drop slowly and it is variable when it reaches its lowest level. If you have also had hormone treatment then your PSA may rise slightly when hormone treatment is stopped because there are still some normal (non-cancerous) prostate cells making PSA.
If your PSA level rises sharply, the doctor may want to do more tests to find out what might be causing this rise and if it might be due to the recurrence of prostate cancer.