If you're diagnosed with prostate cancer, you might need scans to find out the stage of your cancer – in other words, whether it has spread outside your prostate and how far it has spread. The results should help you and your doctor to discuss suitable treatments.
Your doctor or nurse can tell you what scans you might need to have. You might not need a scan if your PSA level is low and your previous results suggest that the cancer is unlikely to have spread.
An MRI (magnetic resonance imaging) scan uses magnets to create a detailed picture of your prostate and the surrounding tissues.
In many hospitals you may have a special type of MRI scan, called a multi-parametric MRI (mpMRI) scan, before having a biopsy. This can help your doctor see if there is any cancer inside your prostate, and how quickly any cancer is likely to grow. In other hospitals, you may have a biopsy first, followed by an MRI scan.
If you had an MRI scan before your biopsy that showed your cancer hasn't spread outside the prostate, you may not need another MRI scan. But if your doctor thinks your cancer may have spread, or if you didn't have an MRI scan before your biopsy, you may have one. It will show whether the cancer has spread outside the prostate and where it has spread to. It will also help your doctor to work out the most suitable treatment options for you.
If you’ve recently had a biopsy, you may need to wait six weeks before you have an MRI scan. This is because the biopsy can cause bruising and bleeding around the prostate, which could affect the scan results.
A CT (computerised tomography) scan can show whether the cancer has spread outside the prostate, for example 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 that 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 up to 20 minutes.
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 scan images to see if there is any cancer in your bones. Areas where the 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 cancer. If it’s still not clear, you may need an MRI scan or, very occasionally, a bone biopsy.
The dye used for a bone scan is safe but it is radioactive. So you should try to avoid close contact with children and pregnant women for up to 24 hours after the scan. And make sure you flush straight away after using the toilet for 24 hours after the scan.
At some hospitals, you may be offered a PET (positron emission tomography) scan. This is more commonly used to see if prostate cancer has come back after treatment, rather than when you are first diagnosed. A PET scan is often combined with a CT scan (PET-CT) to give even more detail about any prostate cancer inside the body. The scan can detect very small areas of cancer.
Your hospital might ask you not to eat or drink for a few hours before the scan. You should avoid vigorous activity for 24 hours before your appointment. Try to wear loose and comfortable clothing for the scan. You’ll need to take off any jewellery or metal items, as these can affect the images.
Before the scan, a small amount of radioactive dye is injected into your arm or hand. There are two main types of dye that can be used – choline and PSMA (prostate specific membrane antigen). You’ll need to sit for an hour – and avoid moving and speaking – while the dye travels around your body and is absorbed. This is because any movement can affect where the dye goes in your body.
You will then lie on a table that will move into the scanner, which is shaped like a large doughnut. The radiographer will leave the room but they can see you and speak to you. The scan usually takes up to 30 minutes. It won’t be painful but you may feel uncomfortable, as you need to lie still as the scanner takes pictures of your body.
The scanner works by detecting the radiation given off by the dye, which collects in areas that may be cancer.
You should be able to go home soon after the scan. You will be asked to avoid contact with children and pregnant women for a few hours after the scan, as you will be giving off a small amount of radiation during this time. Drinking plenty of fluid after the scan can help flush the radiation from your body.
What do my scan results mean?
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.
Read more about what your scan results mean.
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.
Updated: June 2022 | Due for review: June 2025
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- Mottet N, Cornford P, van der Bergh RCN. EAU Guidelines on Prostate Cancer. European Association of Urology; 2022.
- National Institute for Health and Care Excellence. Prostate cancer: diagnosis and management. 2021.