Radiotherapy for prostate cancer uses radiation to kill the cancer cells. This can be done in a couple of different ways, which we will explore, alongside the possible risks that can be associated with radiotherapy.

Who can receive radical radiotherapy?

Radical radiotherapy is another treatment option for prostate cancer. It is suitable for men of any age and is an effective alternative to surgery. The aims of radiotherapy are to destroy prostate cancer cells and to stop them growing.

It is an alternative for men whose cancer can be treated radically, but who are not fit enough or choose not to have an operation.

Radiotherapy does not have risks associated with surgery such as blood clots or blood loss. You will not have to stay in hospital during the therapy and many men are able to continue with their normal daily activities. However, it is not a ‘softer option’ – it carries its own risks and side effects, which you must consider before making this choice.

You can receive radiotherapy in one of two ways:

  • ‘External beam radiotherapy’– high-energy x-ray beams are aimed at the prostate from outside the body.
  • ‘Brachytherapy’– radioactive sources are positioned inside the prostate. There are two types of brachytherapy that can be used for different stages of prostate cancer.

External Beam Radiotherapy

External beam radiotherapy is used to treat prostate cancer by aiming beams of high-energy X-rays at the prostate gland and the tissues immediately around it. The X-rays damage cells and stop them growing. Cancer cells are not able to recover from this damage but the cells in the normal tissues surrounding the prostate (bladder and bowel) can repair themselves more easily.

External Beam Radiothera

Step One
The first step in external beam radiotherapy is to have a special planning scan (CAT scan) of your pelvis. The information on this scan will allow your doctor (oncologist) to see exactly where your prostate is and make a map of the areas that need treatment. During the scan the doctor will place three small dots of ink on your skin. These are permanent ‘dots’ that will be used to make sure you are in exactly the same position for your treatment each day.

Step Two
The doctor will then ask a radiotherapy physicist to make an individual plan for your treatment. They will use a computer programme to decide exactly where the X-rays need to be aimed to treat your prostate gland while trying to avoid as much of the normal tissue in the surrounding areas (bowel, bladder) as possible. This process is very complicated and
will take one to two weeks to be completed.

Step Three
When the doctor is satisfied with your plan, you may need to go back to the radiotherapy department for one final check to position the X-ray beams before the actual treatment starts. This is known as a verification visit.

The X-rays are made in a special machine called a ‘linear accelerator’. When you go for treatment, the radiographer will ask you to lie on your back on a firm bed attached to the machine. Part of the machine will move around you and direct X-rays at your prostate from different directions.

The treatment will only take a few minutes and is completely painless. It is important that you lie very still while the treatment is being given. You may be asked to drink some water before each therapy as this will fill your bladder and reduce the amount of bladder tissue in the
radiotherapy beam.

Step Four

You will have between 20 and 40 treatment sessions over four to eight weeks as an outpatient from Monday to Friday (not weekends). There are two types of external beam radiotherapy that are available. These use different methods to reduce the amount of radiation given to the normal tissues surrounding the prostate gland. This can reduce side effects and also allow higher doses of radiation to be concentrated on the prostate gland itself.

3D conformal radiotherapy uses special ‘blocks’ within the linear accelerator to shape the beams to fit the exact shape and size of your prostate. Intensity Modulated RadioTherapy (IMRT) is a newer type of conformal radiotherapy. It can be used to adjust the dose of radiotherapy that is given to different parts of the treatment area.

Your doctor may recommend that you take a course of hormone therapy before radiotherapy
to shrink the prostate, and maybe afterwards for some months.

What are the side effects of radiotherapy?

Most men experience some side effects, but the severity varies from person to person. Acute side effects happen during treatment and are usually temporary. Late side effects happen after the treatment has finished and these can be permanent. You should be able to continue normal activities during the radiotherapy.

Acute or short-term side effects

These are temporary and usually happen in the last three or four weeks of treatment. They will usually start to get better a few weeks after the treatment is over. You will be given advice about diet and skincare before the treatment starts. Your doctor will prescribe creams and medicines if you need help with any of these problems.

  • Sore skin – you may experience some darkening and soreness of the skin in the area being treated. This is most common in the skin between the legs and around the anus. You should avoid using any creams, lotions or soaps, unless recommended by your doctor, and also avoid hot baths. You may also lose some pubic hair in the area being treated but this will usually grow back.
  • Feeling tired – towards the end of treatment and for a few weeks afterwards, you may feel more tired than usual.
  • Bladder changes – you may have to pass urine more frequently both during the day and at night. Your urine stream may slow down and you may feel a burning sensation (radiation cystitis) when you pass urine.
  • Bowel changes – you may develop some discomfort and pain in the back passage (rectum) and this can be worse when you go to the toilet to open your bowels. This is called proctitis and can be treated with creams and suppositories. Many men find that their bowels become loose and more urgent as the treatment progresses. You may also notice a little leakage from the back passage and occasionally some blood or mucous (slime) in the stools. You will be given advice about diet and medication if diarrhoea becomes a problem.


This form of radiotherapy can be given by:

● low-dose-rate (LDR) permanent seed brachytherapy; or

● high-dose-rate rate (HDR) temporary brachytherapy.

Brachytherapy prostate cancer

Low-dose-rate (LDR) permanent seed brachytherapy

This is an effective treatment for some men with early prostate cancer and uses radioactive seeds. You will be carefully assessed before treatment to make sure that your prostate is not too big, as this treatment can cause difficulties with passing urine if the prostate is very enlarged.

Hollow rods or needles are placed in the prostate through the skin of the perineum (the area between the anus and scrotum). You will need an anaesthetic for this procedure. After the
needles have been placed, you will have a scan (CAT or ultrasound scan) to check their exact position and your doctor and a physicist will use this information to plan your treatment. The needles are withdrawn and the seeds are left permanently inside the prostate where they slowly lose their radioactivity with time and treat the prostate cancer.

Do not worry, you will not be giving out radioactivity or harming anybody who comes into contact with you; although you will be asked to avoid close contact with pregnant ladies and young children for at least 2 months after the treatment as a precaution. This treatment can be a quicker alternative for some of the men who cannot visit a radiotherapy centre each day.

This treatment has similar side effects to external beam radiotherapy but with less chance of erection problems.

High-dose-rate (HDR) temporary brachytherapy

This treatment can be used as well as external beam treatment to allow a higher dose of radiation to be given to the prostate and surrounding tissues for men with locally advanced (see page 28) or high-risk prostate cancer.

The seeds are placed in the prostate in a similar way to that described for LDR brachytherapy, but the needles stay in your prostate for one day during which time you will need to lie on your back and a catheter will be placed in the bladder to help you pass urine. A radioactive source is put in each rod for a few minutes, one or two times during the day. You are not radioactive and the source is removed after each treatment.

You will stay in hospital for a few days until you can pass urine normally after the catheter has been removed. You will have a shorter course of external beam radiotherapy (four to five weeks) two weeks after the brachytherapy treatment. The side effects are similar to external beam radiotherapy apart from a small extra risk of developing a narrowing of the urethra (stricture) which can happen in between six and ten men in every 100 treated.

Permanent or long-term side effects

These side effects can happen many months after the radiotherapy has finished and include the following.

  • Bowel changes – between one and five men in every 100 will have some long-term bowel changes. These can include diarrhoea or urgency to open your bowels, minor bleeding or some mucous from the rectum when passing a motion.
  • Bladder changes – very rarely, men may find it more difficult to pass urine.
  • Sexual changes – most men will have problems getting an erection after radiotherapy, but about half will regain some degree of erection. The risk may increase if you have also been treated with hormone therapy. Treatments may be available to help.
  • Dry orgasm – when you climax, there may be no liquid.

What happens after radiotherapy?

You will be seen in the outpatient clinic a few weeks after the radiotherapy finishes and regularly for many years afterwards. Your PSA will be checked and you will be asked about any side effects from the radiotherapy treatment. If your treatment has been successful, your PSA level should fall. This can take many months and if you are also being treated with hormone therapy, it may be some years before you know your final PSA. This is because the hormone therapy will also reduce the PSA level. You will still have a measurable PSA level because you still have a prostate gland and the normal prostate cells will produce a small amount of PSA.

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