Prostate cancer can spread out of the prostate to other parts of the body. MRI, CT, bone and PET scans can help find out whether the cancer has spread outside the prostate and where it has spread to. The results should help you and your doctor decide which treatments might be suitable for you.

Your doctor or nurse can tell you which scans you might need to have. You might not need a CT or bone scan if your PSA is low and your biopsy results suggest that the cancer is unlikely to have spread.

MRI scan

An MRI (magnetic resonance imaging) scan creates a detailed picture of your prostate and the surrounding tissues.

In some hospitals you might have an MRI scan before your biopsy. This can help your doctor see if there is any cancer in your prostate and where it might be.

If you’ve already had a biopsy, you may need to wait four to six weeks before you have an MRI scan. This is because the biopsy can affect the scan results.

You might have an MRI scan to find out if the cancer has spread.  This will help your doctor to work out the most suitable treatment options for you.

Before the scan the doctor or nurse will ask questions about your health. As the scan uses magnets, they will ask whether you have any implants that could be attracted to the magnet. For example, if you have a pacemaker for your heart you may not be able to have an MRI scan(38). You’ll also need to take off any jewellery or metal items.

You will lie very still on a table, which will move slowly into the scanner. MRI scanners are shaped like a doughnut or a long tunnel. If you don’t like closed or small spaces (claustrophobia), tell your radiographer (the person who takes the images).

The radiographer might give you an injection of a dye during the scan. The dye helps them see the prostate and other organs more clearly on the scan. Let them know if you know you’re allergic to the dye or have any other allergies.

The scan takes 30 to 40 minutes. The machine won’t touch you but it is very noisy and you might feel warm. The radiographer will leave the room but you’ll be able to speak to them through an intercom, and you might be able to listen to music through headphones.

CT scan

A CT (computerised tomography) scan can show whether the cancer has spread outside the prostate, for instance to the lymph nodes or nearby bones. Lymph nodes are part of your immune system and are found throughout your body. The lymph nodes near the prostate are a common place for prostate cancer to spread to. The scan results will help your doctor to work out the most suitable treatment options for you.

Your hospital might ask you not to eat or drink for a few hours before the scan. You’ll need to take off any jewellery or metal items, as these can affect the images.

At your scan appointment, you’ll be given a special dye to help the doctor see the prostate and other organs more clearly on the scan. It’s not radioactive. Most hospitals give you the dye as an injection. But some give the dye as a drink. The dye can give you a warm feeling and you might feel like you need to go to the toilet.

Before your scan appointment let your doctor know if you already know you are allergic to the dye, you have any other allergies, or you are taking the drug metformin for diabetes.

The CT scanner is shaped like a large doughnut. You will lie on a table which moves slowly through the hole in the middle of the scanner. The radiographer will leave the room but you’ll be able to speak to them through an intercom, and they can see you at all times. You will need to keep still, and you might be asked to hold your breath for short periods. The scan will take 10 to 30 minutes.

Bone scan

A bone scan can show whether any cancer cells have spread to your bones, which is a common place for prostate cancer to spread to.

Tell your doctor or nurse if you have arthritis or have ever had any broken bones or surgery to the bones, as these will also show up on the scan.

You might be asked to drink plenty of fluids before and after the scan. A small amount of dye is injected into a vein in your arm and travels around your body. If there is any cancer in the bones, the dye will collect in these areas and show up on the scan. It takes two to four hours for the dye to travel around your body and collect in your bones so you’ll need to wait a while before you have the scan.

You will lie on a table while the scanner moves very slowly down your body taking pictures. This takes around 30 minutes.

The doctor will look at the results of the scan to see whether there is any cancer in your bones. Areas where the radioactive dye has collected may be cancer – these are sometimes called ‘hot spots’. You may need to have X-rays of any ‘hot spots’ to check if they are definitely cancer. If it’s still not clear, you may need an MRI scan. Occasionally, some men have a bone biopsy, but this isn’t very common.

The dye used for a bone scan is safe but it is radioactive. So you may be asked to avoid close contact with children and pregnant women for up to 24 hours after the scan.

PET scan

At some hospitals, you may be offered a PET (positron emission tomography) scan. This shows how well different parts of your body are working. It can be used to check if cancer has spread outside the prostate.

It is normally used to see if your cancer has come back after treatment, rather than when you are first diagnosed.

Getting my scan results

Your doctor or nurse will tell you how long it will take for the results of all the tests to come back. It’s usually around two weeks.

Your doctor will use your scan results to work out the stage of your cancer – in other words, how far it has spread. This is usually recorded using the TNM (Tumour-Nodes-Metastases) system.

  • The T stage shows how far the cancer has spread in and around the prostate.
  • The N stage shows whether the cancer has spread to the lymph nodes.
  • The M stage shows whether the cancer has spread (metastasised) to other parts of the body.

T stage

The T stage shows how far the cancer has spread in and around the prostate. A DRE or MRI scan is usually used to find out the T stage, and sometimes a CT scan.

T1 prostate cancer

The cancer can’t be felt during a DRE or seen on scans, and can only be seen under a microscope.

T1 prostate cancer is small and contained inside the prostate.

 

T2 prostate cancer

The cancer can be felt during a DRE or seen on scans, but is still contained inside the prostate.

T2 prostate cancer

 

T3 prostate cancer

The cancer can be felt during a DRE or seen breaking through the outer layer (capsule) of the prostate.

  • T3a The cancer has broken through the outer layer of the prostate, but has not spread to the seminal vesicles (which produce and store some of the fluid in semen).
  • T3b The cancer has spread to the seminal vesicles.

T3a prostate cancer

T4 prostate cancer

The cancer has spread to nearby organs, such as the bladder, back passage, pelvic wall or lymph nodes.

T4 prostate cancer

N stage

The N stage shows whether the cancer has spread to the lymph nodes near the prostate. Lymph nodes are part of your immune system and are found throughout your body. The lymph nodes near the prostate are a common place for prostate cancer to spread to.

Some lymph nodes are located near the prostate

An MRI or CT scan is used to find out your N stage.

The possible N stages are:

  • NX The lymph nodes were not looked at, or the scans were unclear.
  • N0 No cancer can be seen in the lymph nodes.
  • N1 The lymph nodes contain cancer.

If your scans suggest that your cancer has spread to the lymph nodes (N1), you will be diagnosed with either locally advanced or advanced prostate cancer. This will depend on whether the cancer has spread to other parts of the body.

M stage

The M stage shows whether the cancer has spread (metastasised) to other parts of the body, such as the bones. A bone scan is usually used to find out your M stage. Your doctor may offer you a bone scan if they think your cancer may have spread. You might not need a bone scan if the result is unlikely to affect your treatment options.

The possible M stages are:

  • MX The spread of the cancer wasn’t looked at, or the scans were unclear.
  • M0 The cancer hasn’t spread to other parts of the body.
  • M1 The cancer has spread to other parts of the body.

If you have a bone scan and it shows your cancer has spread to other parts of your body (M1), you will be diagnosed with advanced prostate cancer.

What do my scan results mean?

Your TNM stage is used to work out if your cancer is localised, locally advanced or advanced. This can help your doctor see how far it has spread and which treatment might be suitable for you.

Localised prostate cancer

Cancer that's contained inside the prostate. Possible TNM stages are:

  • T stage: T1 or T2
  • N stage: N0 or NX
  • M stage: M0 or MX.

Locally advanced prostate cancer

Cancer that's started to break out of the prostate, or has spread to the area just outside it. Possible TNM stages are:

  • T stage: T1 or T2
  • N stage: N1
  • M stage: M0

or

  • T stage: T3 or T4
  • N stage: N0 or N1
  • M stage: M0.

Advanced prostate cancer

Cancer that's spread from the prostate to other parts of the body. Possible TNM stages are:

  • T stage: any T stage
  • N stage: any N stage
  • M stage: M1.

What happens next?

Your doctor will look at your test results with a team of health professionals. You might hear this called your multi-disciplinary team (MDT). Based on your results, you and your doctor will talk about the next best step for you.

Read our information for men who've been diagnosed with prostate cancer.

References

Updated: July 2016 | Due for review: July 2018

  • List of references  

    • Haffner J, Lemaitre L, Puech P, Haber G-P, Leroy X, Jones JS, et al. Role of magnetic resonance imaging before initial biopsy: comparison of magnetic resonance imaging-targeted and systematic biopsy for significant prostate cancer detection. BJU Int. 2011 Oct 1;108(8b):E171–8.
    • Kirkham APS, Emberton M, Allen C. How good is MRI at detecting and characterising cancer within the prostate? Eur Urol. 2006 Dec;50(6):1163–1174; discussion 1175.

    • MRI scan - Who can have one? - NHS Choices [Internet]. [cited 2015 Dec 3]. Available from: http://www.nhs.uk/Conditions/MRI-scan/Pages/Who-can-use-it.aspx
    • National Institute for Health and Care Excellence. Prostate Cancer: diagnosis and treatment. Full guideline 175. 2014.