External radiotherapy for metastatic prostate cancer

Radiotherapy means the use of radiation, usually x-rays, to treat cancer. External radiotherapy uses a machine outside the body to direct radiation beams at the cancer.

Metastatic prostate cancer means the cancer has spread from the prostate to other parts of the body. Unfortunately, when prostate cancer spreads, doctors cannot cure it. But treatments like radiotherapy can help to control the cancer. And it can help to reduce symptoms and make you feel better.

You have this treatment in the hospital radiotherapy department. It doesn't hurt, although laying on the radiotherapy couch can be uncomfortable.

You may also have a type of radioisotope therapy Open a glossary item called Radium 223 (Xofigo). This uses a radioactive medicine to treat prostate cancer. We have a separate page about radium 223.

When you might have external radiotherapy for metastatic prostate cancer

You might have radiotherapy to your prostate to help keep the cancer under control. You might also have it to other parts of your body where the cancer has spread. This can help with symptoms like pain or bleeding.

Radiotherapy to your prostate

You might have external radiotherapy to the prostate to try to control the cancer. Your doctor might suggest this if your cancer has only spread to a small number of places in your body.

You usually have it alongside hormone therapy Open a glossary item or after finishing chemotherapy Open a glossary item

Your doctor will tell you how many fractions Open a glossary item of radiotherapy you need. This is usually once a week for 6 weeks if you are having radiotherapy to the prostate. You may also need treatment to other parts of your body such as the bones. 

Radiotherapy to relieve symptoms

This is called palliative Open a glossary item radiotherapy.  You can have it to relieve bone pain. Or to help with spinal cord compression Open a glossary item and relieve other symptoms caused by cancer. Your doctor will try to choose treatments that have as few side effects as possible.

Each palliative radiotherapy treatment takes a few minutes. You might have one dose of radiotherapy to help with the pain. Or a number of treatments over several days. 

Planning your radiotherapy treatment

Before you can start external radiotherapy, your radiotherapy team needs to plan your treatment. This means working out the dose of radiotherapy you need and exactly where you need it. Your planning appointment takes from 15 minutes to 2 hours. 

You usually have a planning CT scan in the radiotherapy department.

The scan shows the cancer and the area around it. You might have other types of scans or x-rays to help your treatment team plan your radiotherapy. The plan they create is just for you.

After your planning session, your radiographers and doctors create your radiotherapy plan. They make sure that the area of the cancer will receive a high dose and nearby areas receive a low dose. This reduces the side effects you might get during and after treatment. It can take a few days or up to 3 weeks before you start treatment.

The radiotherapy room

Radiotherapy machines are very big and could make you feel nervous when you see them for the first time. The machine might be fixed in one position. Or it might rotate around your body to give treatment from different directions. The machine doesn't touch you at any point.

Before your first treatment, your radiographers Open a glossary item will explain what you will see and hear. In some departments, the treatment rooms have docks for you to plug in music players. So you can listen to your own music while you have treatment.

Photo of a linear accelerator

Before each treatment session

You might need to drink a certain amount of water before each treatment. This is to make your bladder comfortably full. This can help to reduce the movement of the prostate between treatments. It can also reduce the radiation dose to the bladder and keep your bowel out of the way. You have to drink the same amount of water each time so that your bladder is the same size.

The radiographers help you to get into position on the treatment couch. They line up the radiotherapy machine using the marks on your skin. 

Then the radiographers leave you alone in the room for up to 25 minutes. They will tell you what to do if you need help during this time.

During the treatment

You need to lie very still. Your radiographers might take images (x-rays or scans) before your treatment. This is to make sure that you're in the right position. The machine makes whirring and beeping sounds. You won’t feel anything when you have the treatment.

Your radiographers can see and hear you on a CCTV screen in the next room. They can talk to you over an intercom and might ask you to hold your breath or take shallow breaths at times. You can also talk to them through the intercom or raise your hand if you need to stop or if you're uncomfortable.

You won't be radioactive

This type of radiotherapy won't make you radioactive. It's safe to be around other people, including pregnant women and children.

Travelling to radiotherapy appointments

You might have to travel a long way each day for your radiotherapy. This depends on where your nearest cancer centre is. This can make you very tired, especially if you have side effects from the treatment.

You can ask your radiographers for an appointment time to suit you. They will do their best, but some departments might be very busy. Some radiotherapy departments are open from 7 am till 9 pm.

Car parking can be difficult at hospitals. Ask the radiotherapy staff if you are able to get free parking or discounted parking. They may be able to give you tips on free places to park nearby.

Hospital transport may be available if you have no other way to get to the hospital. But it might not always be at convenient times. It is usually for people who struggle to use public transport. Or who have any other illnesses or disabilities. You might need to arrange hospital transport yourself.

Some people are able to claim back a refund for healthcare travel costs. This is based on the type of appointment and whether you claim certain benefits. Ask the radiotherapy staff for more information about this and hospital transport.

Some hospitals have their own drivers and local charities might offer hospital transport. So do ask if any help is available in your area.

Side effects of external radiotherapy

You have side effects if you have radiotherapy to the prostate to try to control your cancer. This includes loose or watery poo (diarrhoea) and passing urine more often.  

Palliative radiotherapy aims to make you feel better. Your doctor will try to choose treatments that have as few side effects as possible. The side effects from palliative radiotherapy aren't usually that bad but you might have a few side effects. The effects vary, depending on which part of your body the doctor treats.

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  • Prostate cancer: ESMO clinical practice guidelines for diagnosis, treatment and follow up
    C Parker and others
    Annals of Oncology, 2020. Vol 31, Issue 9. Pages 1119-1134

  • Cancer: Principles and practice of oncology (12th edition)
    VT De Vita, TS Lawrence and SA Rosenberg
    Lippincott, Williams and Wilkins, 2023

  • External beam radiotherapy for patients presenting with hormone sensitive, low volume metastatic prostate cancer at the time of diagnosis
    NHS England, 2021

  • Radiotherapy to the primary tumour for newly diagnosed, metastatic prostate cancer (STAMPEDE): a randomised controlled phase 3 trial
    C Parker and others
    The Lancet, 2018. Vol 392, Issue 10162. Pages 2353-2366

  • Management of Patients with Advanced Prostate Cancer. Report from the 2024 Advanced Prostate Cancer Consensus Conference (APCCC)
    S Gillessen and others 
    European Urology, 2025. Volume 87, Issue 2, Pages 157 - 216

Last reviewed: 
23 Jul 2025
Next review due: 
23 Jul 2028

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