External radiotherapy for prostate cancer | Cancer Research UK
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External radiotherapy for prostate cancer

This treatment uses a high dose of radiation just to the area of the prostate gland. You can have this treatment if your prostate cancer is only in the prostate gland or has just broken through the prostate capsule. If it has spread any further, this treatment is not likely to cure it.

How you have the treatment

You usually have a course of daily treatments lasting from 4 to 8 weeks. During that time you go to the hospital radiotherapy department each day from Monday to Friday. The appointment takes between 15 to 30 minutes each time.

Side effects

Some side effects usually come on gradually as you go through your course of treatment. They include sore skin in the treatment area, irritation of the bladder, needing to pass urine more often, diarrhoea, and tiredness.

Your side effects may last for several weeks after your treatment has finished. The tiredness can last for some months.

Long term side effects

Some men have long term problems after this type of treatment. Unfortunately, doctors cannot tell who will be affected. 

Many men have problems getting an erection. Some men have problems passing urine. Some have a straining feeling in the back passage, called proctitis. Radiotherapy for prostate cancer can also increase the risk of cancer of the back passage (rectum). 


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Using external radiotherapy for prostate cancer

External radiotherapy treatment uses a high dose of radiation just to the area of the prostate gland. Your treatment team will make sure the whole of your prostate gland is treated as well as an area of 1 to 2 centimetres around it. 

This is to make sure that any cancer cells a little way away from the main tumour are treated. These cells are called microscopic spread. They are too small to be seen on scans, but if they are not treated the prostate cancer is more likely to come back in the future.

You can have external radiotherapy treatment if your prostate cancer is between stage T1 and T3. This means that the cancer can have spread through the covering of the prostate gland (the capsule). But it must not have spread any further. If it has spread further, this treatment is not likely to cure it. And because of the side effects, it may not be the best treatment for you.


How and where you have radiotherapy

You have to travel to hospital for radiotherapy treatment. You have it in the radiotherapy outpatient department. 

The radiotherapy dose is split into a course of small treatments. If you were to have the total dose in one go, it would harm normal body tissues too much. So you have a small dose each day over a number of weeks. Doctors call each dose a fraction.

External radiotherapy treatment can be given in different ways. But you usually have it once a day, for 5 days each week, from Monday to Friday. It takes about 4 to 8 weeks.


Planning your treatment

Before you begin your treatment, the radiotherapy team carefully plan your external beam radiotherapy. This means working out how much radiation you need to treat the cancer and exactly where you need it. 

Your planning appointment may take from 15 minutes up to a couple of hours. You will have a planning CT scan. The scan shows the cancer and the structures around it.

You may need to have fiducial markers (metal markers) put into your prostate. You have this as an outpatient appointment under a local anaesthetic before the planning scan. These help the machine give a more accurate treatment.

Before you have the scan, you may have to empty your bowels and bladder. The radiographers may need you to take an enema to help you empty your bowels. They will explain how it works. You may have to drink a certain amount of water too. 

This depends on what type of radiotherapy treatment your doctor has prescribed you to have. If you are given any instructions, you have to follow these before every treatment, to make sure your bowels and bladder are the same size for everytime. 

It is easy for the bladder and bowel to change shape depending on whether they are empty or not. This has an effect on the treatment. It could mean that the bladder and bowels are over or under dosed which could increase your side effects.

CT scanner

You lie on the scanner couch with the treatment area exposed. The radiographers will put some markers on your skin. You need to lie very still. Once you are in position the radiographers move the couch up and through the scanner. The scanner is a doughnut shape. 

The radiographers leave the room and the scan starts. It takes up to 5 minutes. You won't feel anything. The radiographers watch from the next door room.

Before the planning appointment you may also have other scans, such as an MRI scan. Your treatment team can feed the other scans into the planning scanner.

Ink marks

Once the treatment team has planned your radiotherapy, they may put ink marks on your skin to make sure they treat exactly the same area every day. They may also make pin point sized tattoo marks in these areas.

After your planning session

You may have to wait a few days or up to 2 weeks before you start treatment. During this time the physicists and your radiotherapy doctor decide the final details of your plan. 

Your doctor will plan the areas that need treatment and outline areas to limit the dose to or avoid completely. They call this contouring. Then the physicists and staff called dosimetrists plan the treatment very precisely using advanced computers.


Having radiotherapy

Radiotherapy machines are very big. The machine may be fixed in one position or able to rotate around your body to give treatment from different directions. Before your first treatment your radiographers will explain what you will see and hear. The treatment rooms usually have docks for you to plug in music players. So you can listen to your own music.

You can't feel radiotherapy when you actually have the treatment. It takes anything from 1 minute to several minutes. It is important to lie in the same position each time, so the radiographers may take a little while to get you ready.

A photo of a linear accelerator, which gives radiotherapy

Once you are in the right position the staff leave you alone in the room for about 15 to 30 minutes. They watch you carefully on a closed circuit television screen.

Our page about having external radiotherapy has a video about having radiotherapy that you may want to watch.

External radiotherapy doesn't make you radioactive. It is perfectly safe to be with other people, including children, throughout your course of treatment.


Temporary side effects

You will probably have some side effects from radiotherapy treatment. The most common ones are

  • An inflamed bladder, making you want to pass urine very often
  • An inflamed bowel, causing diarrhoea
  • Tiredness
  • Sore skin in the area of the prostate and around the back passage
  • Loss of pubic hair

Your side effects may last for several weeks after your treatment has finished. Tiredness can last for some months afterwards.


Long term side effects

External radiotherapy can have side effects that last for longer than a few weeks. For most men, these symptoms settle down gradually but for some they are permanent. Unfortunately, your doctor cannot tell before you are treated whether you are likely to have permanent side effects. 

Possible permanent side effects include

  • Bowel problems
  • Problems getting an erection (impotence)
  • Problems passing urine
  • A slight increase in the risk of rectal cancer

More about prostate cancer radiotherapy

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Updated: 1 October 2014