Radiotherapy and locally advanced prostate cancer

Radiotherapy is a treatment that uses high-energy X-rays to kill cancer cell. Radiotherapy and hormone therapy are usually used together to treat locally advanced prostate cancer.

Hormone therapy helps to make the radiotherapy work better at controlling your prostate cancer. It may be given for different lengths of time before during and or after radiotherapy.

Planning your treatment

Before radiotherapy is given, your doctor will plan how best to give your treatment. This doctor is known as a radiation oncologist. He or she will decide how much radiotherapy is needed to treat your cancer while limiting any damage to normal cells. On your first visit to the radiotherapy unit, you will have an MRI or CT scan to show the area being treated. It will take a few visits before your treatment can go ahead. 

The radiation therapist will mark the area on your skin where you are to receive treatment. This is done so that the X-rays can be aimed at the same area each day. Before starting radiotherapy, your radiation therapist and nurse will tell you how to look after your skin during and after treatment.

Getting your radiotherapy 

Having radiotherapy is quite straightforward. You will visit the unit every day during the week with a rest at weekends. A course of radiotherapy may continue for 7–8 weeks. Each treatment session only takes a few minutes. You will not feel any pain during treatment but you will have to lie very still. How much treatment you receive will depend on the extent of the cancer. Your doctor will discuss your treatment with you.

Special diet and fluids

It is important that your prostate gland is in the same position every time you have your treatment. The exact position of your prostate can be affected by having a full bladder or a full bowel. To make sure your prostate is in the same position each time, the staff in the radiotherapy unit may ask you to follow a special diet, drink some water just before your treatment, or give you an enema beforehand.

Having treatment

Before you have each treatment, the staff will help you into the right position on the radiotherapy table. They will use the marks on your body to make sure that the treatment is given to the right spot each time. Before the treatment starts, the staff will leave the room. They can see and hear you at all times and you can talk to them. During the treatment the machine will move around your body, but it does not touch you and you will not feel anything.

After treatment

The radiation does not stay in your body after the treatment, so it is perfectly safe to be around other people at all times afterwards. Treatment affects people in different ways. You might be able to continue your normal activities, such as work or social activity, or you might feel that you need more rest than usual.

Side-effects of external beam radiation

Side-effects occur when the normal healthy cells near the treated area are exposed to the beam of radiation. Some side-effects appear during the treatment while others can develop afterwards. 

The most common side-effects are those that develop during or shortly after your treatment. Not all men will get all of the side-effects, but there is no way of knowing which of them you will get or how much trouble they will cause you. During your treatment, your radiation therapists can discuss your side-effects and advise you on how best to manage them. 

Urinary problems

During radiotherapy your bladder may become irritated. This can make you pass urine more often, during the day and at night. On your way home from each treatment you may need to stop to pass urine, especially if you are asked to drink water before each treatment.

Radiotherapy can also cause a burning feeling when you pass urine. Sometimes drinking too much tea, coffee, cola or alcohol can make these problems worse. If this happens, reduce your intake of these drinks for a time and drink more water, juices or soft drinks. You may notice a trace of blood in your urine too. If you have problems passing urine or pass blood, discuss it with your doctor, nurse or radiation therapist. 

These symptoms usually start to settle down some weeks after your treatment has finished. But for some men they continue long term. Your bladder might be permanently affected by radiotherapy. This happens with a very small number of men. As well as the short-term symptoms you might develop a narrowing of your urethra (water pipe). This can make it difficult to pass urine and needs to be treated with surgery.

Sometimes the blood vessels in your bladder can become more fragile after radiotherapy. This can take many months or years to happen and causes some blood to appear in your urine. If you notice any bleeding, tell your doctor so that tests can be done and proper treatment given. Rarely, radiotherapy can cause leakage of urine due to damage to the nerves that control your bladder muscles. But this is unlikely unless you have had prostate surgery as well. If this happens, discuss it with your doctor or nurse.

If you would like to read further information about urinary problems visit our section Urinary symptoms, catheters and prostate cancer treatment or call the Cancer Nurseline on 1800 200 700 to speak to a cancer nurse in confidence. You can also talk to a nurse at your local Daffodil Centre.  

Bowel problems

You might develop diarrhoea during radiotherapy. This is because your prostate gland is very close to your back passage (rectum). Passing watery bowel motions more than twice a day is known as diarrhoea. You may also have cramping tummy pain and pass more wind and mucus. If this happens, drink lots of fluids to replace the fluids you are losing.  Let your doctor or radiation therapist know if you have diarrhoea. There is medication that can stop this side-effect. You might also notice that you need to get to the toilet more quickly.

Including too much fibre in your diet during radiotherapy may make the diarrhoea worse for some men. In this situation eating less fibre may be helpful. 

It is important to talk to your radiation therapist, doctor or nurse before making any changes to your normal diet if you are experiencing symptoms.

Low fibre foods include potatoes (peeled), white rice and pasta. It might also help to avoid gassy foods like beans, beer, fizzy drinks and green leafy vegetables like cabbage/ cauliflower/sprouts as well as high-fibre bread and whole grains cereals and fresh fruit. Eat and drink slowly and chew your food more slowly. 

On the other hand, you might have more difficulty opening your bowels and become constipated.  You might feel like you have not emptied your bowel properly after going to the toilet. Your doctor and nurse will help you find ways to manage your bowel symptoms during your treatment. Again, these symptoms usually start to settle down a short time after your treatment has stopped. 

Before your treatment starts it is important to tell your doctor if you have had other bowel problems in the past as this may increase your chance of developing bowel problems during and after the radiotherapy treatment. Your radiation therapist or nurse may give you a specific dietary advice sheet to follow while undergoing the radiation treatment. It may also be possible to speak with the dietician in the hospital for further advice if you need it.

In some cases bowel problems might persist. Or they might develop years after treatment and you find that your bowel habits change permanently. Bowel motions may be more urgent and frequent after radiotherapy. This may mean you open your bowels a little more often than you did before your treatment.

Tell your doctor about any bowel problems that you have, as there are treatments that can help. The blood vessels in your bowel can also become more fragile after radiotherapy. This can cause blood to appear in your bowel motions. As other bowel problems are common in older men, it is also possible that symptoms are due to something else. You may need to have a few tests done to find out the cause of your symptoms. Tell your doctor or nurse if you have on-going problems with diarrhoea or bleeding from the rectum (back passage).

For advice on eating well during radiotherapy, call our Cancer Nurseline on 1800 200 700. You can also download or request a free copy of the booklet Diet and Cancer. You could also pick one up in your local Daffodil Centre

Discomfort at your back passage

Radiotherapy to your prostate area may irritate your back passage and cause discomfort. It can also cause soreness around your anus. You may notice some blood on toilet tissue after passing a bowel motion. Indeed, it may feel as if you have piles. If this happens, tell your doctor or nurse. Your doctor can prescribe medication that will help this problem.

Skin changes

During radiotherapy, the skin on your bottom or between your legs may become sore and a bit darker. It may even look like sunburn. It is best to avoid hot baths and to wear loose cotton clothes at this time. When you wash the area, use warm water and pat it dry with a soft towel. Do not rub the skin while washing and drying. You can use a special cream to treat this problem but be sure to only use creams recommended by your nurse or radiation therapist. Avoid perfumed creams or powders. Check with your radiation therapist or nurse before applying anything to your skin.

Fatigue (tiredness)

Tiredness can build up over the course of your treatment. You may feel tired because of the treatment itself or perhaps you have to travel long distances for treatment. Rest as much as you need to and continue to do the things you like, but remember you may have less energy than before treatment. Regular gentle exercise such as walking can help to manage tiredness and increase your energy levels.

Depending on your job, you might continue to work during treatment or else take time off work. You may feel tired for some time but most men recover from their tiredness within a couple of months of finishing their treatment.

If you are having trouble with fatigue, a helpful booklet called Coping with Fatigue is available to download. Call our Cancer Nurseline on Freephone 1800 200 700 if you would to have a copy posted to you and to get information, support and advice from a  cancer nurse. You can also visit your local Daffodil Centre. Find your nearest Daffodil Centre.

Erectile dysfunction

Radiotherapy to your prostate can cause damage to the nerves and blood vessels that control erections. As a result, it can be difficult to get and keep an erection.

This is especially so if you are taking hormone therapy as well.

There is some evidence that taking tablets or using vacuum therapy for erectile dysfunction soon after radiotherapy may reduce your risk of erectile problems.At this time you may not be even interested in sex. But taking the tablets or using a vacuum pump at an early stage may improve your chances of getting erections when you are ready to think about sex again. You can discuss this with your doctor, nurse or GP. After radiotherapy, some men find that an orgasm has less semen than usual and they have an orgasm where no semen is ejaculated. 

For more information visit the section Sex, erectile dysfunction and prostate cancerPlease call our Cancer Nurseline on Freephone 1800 200 700 if you would like a copy posted or if you would like to talk to a cancer nurse.

You might also find it helpful to read the section on Communication and intimacy with your partner, which has tips on being intimate after prostate cancer treatment and contact details for professionals who can help. You can also read further information about sex and prostate cancer. You can also get information and support from your local Daffodil Centre. Find your nearest Daffodil Centre.


Radiotherapy for prostate cancer may cause infertility. If this happens, it means you cannot father a child in the future. If this is important to you, talk to your doctor about this effect before your treatment. 

Side-effects in general

If you would like more information on radiotherapy you can read our Understanding Radiotherapy booklet. Call our Cancer Nurseline on 1800 200 700 for a free print copy. You can also visit a Daffodil Centre, where you can get copies of our booklets or talk to a cancer nurse in confidence.

You might also like to view our webpage on radiotherapy. A helpful booklet on radiotherapy treatment to the male pelvis is available from the Health Service Executive. You can also download our booklet Understanding prostate cancer.

Follow-up after radiotherapy

No matter what treatment you receive, you will still need to come back for regular check-ups. This is called follow-up. At each outpatient visit, your doctor or nurse will check your blood test results, including your PSA, and ask you how you are.

At some appointments a rectal exam will be done too. Other tests, like X-rays and scans, can be arranged if needed. The visits will allow your doctor to monitor your progress and follow up on any on-going side-effects that you may have. He or she can also check for new side-effects that may develop. It is better to be aware of side-effects as early as possible so that you can be given advice and treatment to help manage them.

It is important that you tell the doctor or nurse how you have been since your last appointment. Remember to tell them about any new symptoms, aches or pains you have. Sometimes it helps to write down what you want to say before you see the doctor. If you are between check-ups and have a symptom or problem that is worrying you, let your doctor or specialist nurse know. Make an appointment to see him or her as soon as possible. 

Date Last Reviewed: 
Monday, January 28, 2019