Radiotherapy treats cancer by using high-energy x-rays to destroy the cancer cells, while doing as little harm as possible to normal cells. Radiotherapy for cancer of the prostate is usually given from an external machine (external beam radiotherapy), but for some men with early prostate cancer it can be given by inserting small radioactive seeds into the tumour (brachytherapy). External radiotherapy and brachytherapy both appear to be equally effective in curing prostate cancer. Your doctor may suggest that you have hormonal therapy before or after your radiotherapy.

In early prostate cancer, the radiotherapy is given to the prostate gland. The aim is to destroy the cancer cells, while doing as little harm as possible to normal tissues in the surrounding area such as the bladder or back passage (rectum). This is known as radical radiotherapy.

Radiotherapy is given in the hospital radiotherapy department, usually as daily sessions from Monday to Friday, with a rest at the weekend. For early prostate cancer, the course of treatment may continue from 4-7 weeks.

Planning is a very important part of radiotherapy and may take one or two visits. The treatment has to be carefully planned to make sure that it is as effective as possible. You will be asked to have a CT scan or lie under a machine called a simulator, which takes x-rays of the area to be treated. The treatment is planned by a cancer specialist (clinical oncologist).

Marks are usually drawn on your skin to help the radiographer (who gives you your treatment) to position you accurately and to show where the rays will be directed. These marks must stay in place throughout your treatment, and permanent marks (like tiny tattoos) may be used. These are tiny, and will only be done with your permission. You may feel a little uncomfortable while it is being done.

At the beginning of each session of radiotherapy, the radiographer will position you carefully on the couch, and make sure you are comfortable. During your treatment you will be left alone in the room but you will be able to talk to the radiographer who will be watching you. Radiotherapy is not painful but you have to lie still for a few minutes while the treatment is being given.

Conformal radiotherapy (CRT) or intensity modulated radiotherapy (IMRT) are usually used.

In conformal radiotherapy, a special attachment to the radiotherapy machine carefully shapes the radiation beams to match the shape of the prostate gland. Shaping the radiotherapy beams reduces the radiation received by the healthy cells in nearby organs such as the bladder and rectum. This reduces the side effects of radiotherapy treatment and may allow higher doses to be given, which could be more effective.

IMRT is a newer, more complex type of conformal radiotherapy and allows the radiotherapist to vary the dose of radiation given to different parts of the tumour and surrounding tissue. It is not yet known whether IMRT is better than conformal radiotherapy.

Radiotherapy to the prostate can make it more difficult to have an erection. There are various treatments which can help (see dealing with side effects).

Radiotherapy to the prostate area may irritate the rectum, and cause discomfort and diarrhoea. It may cause soreness around the anus. Your doctor can prescribe medicines to reduce this and you may be advised to change your diet.

The radiotherapy may also cause cystitis, which can make you want to pass urine more often or cause a burning feeling when you pass urine. Your doctor can prescribe medicines to reduce this. These effects usually disappear gradually a few weeks after the treatment has ended. Rarely, if you have difficulty in passing urine, it may be necessary to have a urinary catheter put in.

Radiotherapy can also cause general side effects such as tiredness, which are mild for some men and more troublesome for others. The radiographer will be able to advise you what to expect. Try to balance rest with regular, gentle exercise, especially if you have to travel a long way for treatment each day.

The radiotherapy may make some of your pubic hair fall out. When you have finished the course of treatment, the hair will grow back. However, the hair may be thinner or finer than it was before.

Most side effects of radiotherapy gradually disappear once the treatment has ended. However, others may continue for some months and some may even be permanent. If you have any problems during your treatment, talk to the radiotherapy staff as they will be able to help you.

Radiotherapy does not make you radioactive and it is perfectly safe for you to be with other people, including children, throughout your treatment.

Our general information section on radiotherapy gives more details about this treatment and its side effects.

Although radiotherapy can get rid of the cancer cells completely for many men, in about 1 in 3 men (33%) the cancer cells may come back in the area of the prostate at some time after the treatment. In this situation, surgery can very occasionally be done to remove the prostate gland. This type of surgery is known as salvage surgery.

Radiotherapy to the prostate area can sometimes lead to long-term problems.

Radiotherapy for prostate cancer can cause an inability to have an erection (impotence) in about 3-5 in 10 (30-50%) of the men who have this treatment; this may develop over a period of 2-5 years.

Our page on dealing with side effects discuss ways of coping with erection problems. This side effect of treatment can be very difficult to deal with and can affect your sex life and your relationship with your partner. You may find it helpful to read our section on sexuality. Many organisations offer counselling for sexual or relationship problems.

In a number of men, the bowel or bladder may be permanently affected by the radiotherapy. The blood vessels in the bowel and bladder can become more fragile and this can make blood appear in the urine or when you pass bowel motions. This can take many months or years to occur. If you notice any bleeding, it is important to let your doctor know so that tests can be carried out and appropriate treatment given. Occasionally bowel movements may be more urgent after radiotherapy and, rarely, there may be some difficulty in controlling the bowels.

Often, radiotherapy can help to improve problems with passing urine, but for some men radiotherapy can lead to leakage of urine due to damage to the nerves that control the bladder muscles (urinary incontinence). This is unlikely unless you have had a TURP or prostatectomy as well. If this happens it is important to discuss it with your doctor, who can arrange for you to see a specialist continence nurse. You may also find it helpful to contact the Continence Foundation.

If radiotherapy has been given to the lymph glands in the pelvic area as well as to the prostate, it can cause some swelling of the legs, known as lymphoedema.

We have further information about the long-term side effects of pelvic radiotherapy.

This type of radiotherapy is available in some hospitals in the UK. It is also sometimes called internal radiotherapy, implant therapy or seed implantation. It can be carried out under a general anaesthetic or a spinal anaesthetic (epidural). Small radioactive metal ‘seeds’ are inserted into the tumour so that radiation is released slowly over a period of time. The seeds are not removed but the radiation gradually fades away over about six months. There is no risk of it affecting other people.

Before the seeds are put into the prostate, a study of the prostate gland will be done (known as a volume study). This is to confirm the exact size and position of the prostate gland. For 24 hours before the volume study you will need to follow a special diet to make sure that your bowel is empty. You will also be given an enema to empty your bowel, so that the ultrasound picture is as clear as possible. The volume study is done in the operating theatre and you will need to have an anaesthetic for a short time.

A trans-rectal ultrasound is used to take pictures of the prostate. These provide a three-dimensional model which is then used to decide the number of seeds needed for treatment, and exactly where they should be put.

The implant procedure takes about one hour. An ultrasound probe is inserted into the rectum to show the prostate. Around 80-100 radioactive seeds are then inserted through the skin between the prostate and the anus, and guided into the prostate gland. As the procedure may cause some swelling of the prostate, which can lead to blockage of the urethra, a catheter is sometimes inserted into the bladder to drain urine. This may be removed after a couple of hours or left in place overnight.

Antibiotics are given after the implant, to prevent infection. Most men go home the day after the implant, but some leave hospital as soon as they have recovered from the anaesthetic and are able to pass urine normally. After the implant it is best to avoid heavy lifting or strenuous physical activity for two or three days.

All the radioactivity is absorbed within the prostate and so it is completely safe for you to be with other people. However, women who are (or could be) pregnant and children should not stay very close to you for long periods of time. You should not let children sit on your lap, but can hold or cuddle them for a few minutes each day and it is safe for them to be in the same room.

The seeds stay permanently embedded in the prostate gland, but there is a tiny chance of a single seed being passed in the semen during sexual activity. So it is advisable to use a condom for the first few weeks after the implant. During this time the semen may be coloured black or brown - this is normal and is due to bleeding that may have occurred during the procedure. Condoms should be disposed of in the dustbin and should be double-wrapped.

Side effects of brachytherapy

Brachytherapy causes similar side effects to external beam radiotherapy. It is also common to feel mild soreness, and to have some bruising and discoloration between the legs for a few days after the procedure. Your doctor can prescribe painkillers to relieve this.

You may also notice some blood in the urine. This is quite normal but if it becomes severe or there are large clots present you should let your doctor know immediately. It is important to drink plenty of water to help prevent blood clots and flush the bladder.

As with external radiotherapy, erection problems develop in 3-5 in 10 (30–50%) of men some years after the treatment.

Brachytherapy may be less likely to affect the bowel than external beam radiotherapy, although the risk of urinary problems (such as narrowing of the urethra) is higher. Up to one in seven men may not be able to pass urine immediately after the procedure and may need to have a catheter inserted for a while. Some men may develop narrowing of the urethra some time later, which may cause problems with passing urine.

The risk of leakage of urine is about 1 in 100 (1%). Some men find that they have pain or discomfort on passing urine, need to pass urine more often or have a weaker urine stream. This is usually due to the radiation from the seeds in the prostate and improves over 3-12 months as the seeds lose some of their radioactivity. Drinking plenty of fluids and avoiding caffeine may help to reduce these effects.