External radiotherapy for metastatic prostate cancer

External radiotherapy is a possible treatment for metastatic or advanced prostate cancer. Metastatic prostate cancer means the cancer has spread from the prostate to other parts of the body. 

When prostate cancer is advanced, it can no longer be cured. Radiotherapy treatment can often control the cancer, 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 internal radiotherapy called Radium 223 (Xofigo).

When you might have external radiotherapy for metastatic prostate cancer

You might have external radiotherapy to relieve symptoms such as pain caused by prostate cancer spread. Or to help control the cancer.

Radiotherapy to relieve symptoms

This is called palliative treatment.

You might have 1 treatment or a few treatments given over a few days. These treatments are sometimes known as fractions.

Radiotherapy to help control the cancer

You might have external radiotherapy to the prostate to try to control the cancer. You usually have it alongside hormone therapy or after finishing chemotherapy. 

Your doctor will tell you how many treatments or fractions 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. If this happens, you usually have between one and 5 radiotherapy treatments.

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 therapy 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 so that your bladder is full. This can help to reduce the movement of the prostate between treatments and reduce the radiation dose to the bladder. 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.

During the treatment

You need to lie very still. Your radiographers might take images (x-rays or scans) before your treatment 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 the therapy radiographers Open a glossary item 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 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 might have a few side effects with palliative radiotherapy. The effects vary, depending on which part of your body is treated.

You have more 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.  

  • Prostate cancer: diagnosis and management
    National Institute for Health and Care Excellence (NICE), 2019. Last updated December 2021

  • 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 (11th edition)
    VT De Vita, TS Lawrence and SA Rosenberg
    Lippincott, Williams and Wilkins, 2019

  • 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

Last reviewed: 
27 Jul 2022
Next review due: 
27 Jul 2025

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