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TNM Staging

The TNM staging system is the most common way that doctors stage prostate cancer. TNM stands for Tumour, Node, Metastasis. Doctors may also use the number staging system. Or your doctor might describe your cancer as localised, locally advanced or advanced.

Knowing the stage of your cancer helps your doctor to work out what treatment you need. They use the information about the stage of your cancer along with:

  • the result of your PSA blood test 
  • what your cells look like under a microscope (the Gleason score)  

Tumour (T)

Tumour describes the size of the tumour (area of cancer). This is a simplified description of the T stage.

There are 4 main stages of cancer size in prostate cancer – T1 to T4.

T1

T1 means the cancer is too small to be seen on a scan, or felt during examination of the prostate.
It’s divided into T1a, T1b and T1c.

T1a means that the cancer is in less than 5% of the removed tissue. Your surgeon unexpectedly finds T1a cancers during surgery for other reasons. 

T1b means that the cancer is in 5% or more of the removed tissue. Your surgeon unexpectedly finds T1b cancers during surgery for other reasons. 

T1c cancers are found by biopsy, for example after a raised PSA level.

T2

T2 means the cancer is completely inside the prostate gland. It’s divided into T2a, T2b and T2c.

T2a means the cancer is in only half of one side of the prostate gland.

T2b means the cancer is in more than half of one side of the prostate gland, but not both sides. 

T2c means the cancer is in both sides but is still inside the prostate gland.

T3

T3 means the cancer has broken through the capsule (covering) of the prostate gland. It’s divided into T3a and T3b.

T3a means the cancer has broken through the capsule (covering) of the prostate gland.

T3b means the cancer has spread into the tubes that carry semen (seminal vesicles).

Diagram showing TNM stages for prostate cancer.jpg

T4

T4 means the cancer has spread into other body organs nearby, such as the back passage, bladder, or the pelvic wall.

Diagram of the prostate showing a T4 sized tumour

Node (N)

Node (N) describes whether the cancer has spread to the lymph nodes.

N is split into N0 and N1. 

N0 means that the nearby lymph nodes don’t contain cancer cells

N1 means there are cancer cells in lymph nodes near the prostate

Diagram showing the lymph nodes around the prostate

Metastasis (M)

Metastasis (M) describes whether the cancer has spread to a different part of the body.

There are 2 stages of metastasis – M0 and M1.

M0 means the cancer hasn’t spread to other parts of your body.

M1 means the cancer has spread to other parts of the body outside the pelvis. It is split into M1a, M1b and M1c.

M1a means there are cancer cells in lymph nodes outside the pelvis

M1b means there are cancer cells in the bone

M1c means there are cancer cells in other parts of the body

Diagram showing metastasis of prostate cancer

Treatment

The stage of your cancer helps your doctor to decide which treatment you need. Treatment also depends on:

  • what the cancer cells look like under the microscope (Gleason score)
  • your PSA blood test level
  • your type of cancer (the type of cells the cancer started in)
  • your age and general health
  • how you feel about what the treatments involve and the side effects

You might not have treatment straight away. Sometimes your doctor monitors your cancer and starts treatment if the cancer begins to grow. Depending on your situation, they may call this:

  • active surveillance
  • watchful waiting

If you have treatment this might include:

  • surgery to remove your prostate
  • external radiotherapy
  • internal radiotherapy (brachytherapy)
  • hormone therapy
  • chemotherapy
  • symptom control treatment
  • high frequency ultrasound therapy (HIFU) as part of a clinical trial
  • cryotherapy as part of a clinical trial
Last reviewed: 
15 Jul 2019
  • AJCC Cancer Staging Manual (7th Edition)
    American Joint Committee on Cancer, 2010

  • Cancer of the prostate: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up
    C Parker and others,
    Annals of Oncology, 2015. Volume 26, Pages 569-577

  • Prostate cancer: diagnosis and management
    National Institute for Health and Care Excellence (NICE) guidelines, 2019. 

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