Staging and grading

The results of your tests will tell your doctors more about the size of your tumour and whether it has spread beyond the prostate gland. This is known as the stage of the cancer. They also give information about how fast it might grow. This is the grade of the cancer.

The TNM system describes the size of the tumour, whether the cancer has spread to the lymph nodes and whether the cancer has spread to other organs.

The Gleason system is the most commonly used grading system for prostate cancer. It looks at the patterns of the cancer cells in the prostate.

Advanced prostate cancer has spread to other structures close to the prostate such as the bladder. Or it has spread to more distant parts of the body such as the bones. If you would like more information about the staging and grading of your cancer you should talk to your doctor.

Staging

The stage of a cancer is a term used to describe its size and whether it has spread. Knowing the stage of your cancer helps doctors decide the best treatment for you.

The most commonly used systems are a number staging system and the TNM staging system.

Number staging

The simplified numbered staging system is described below:

  • Stage 1 – The cancer is very small and only in the prostate.
  • Stage 2 – The cancer is more advanced than stage 1, but it’s still within the prostate gland.
  • Stage 3 – The cancer has started to break through the outer capsule of the prostate gland and may be in the nearby tubes that transport semen (seminal vesicles).
  • Stage 4 – The cancer has spread beyond the prostate gland to nearby structures such as the bladder or back passage (rectum), or to more distant organs such as the bones or liver.


TNM staging

This system is more complex and can give more precise information about the tumour stage.

T stands for tumour

Doctors put a number next to the ‘T’ to describe the size and spread of the cancer.

  • T1 – The tumour is within the prostate gland. It is too small to be detected during an examination of the prostate, but may be picked up through tests such as a PSA test and a biopsy. There are generally no symptoms with T1 tumours.
  • T2 – The tumour is still within the prostate gland, but is large enough to be felt during an examination of the prostate gland. Often there are no symptoms.

The T2 stage is divided into:

T2a – The tumour is only in one half of one of the two lobes that make up the prostate gland.

T2b – The tumour is in more than one half of one of the lobes in the prostate gland.

T2c – The tumour is in both lobes of the prostate gland.

T1 and T2 tumours are known as early (localised) prostate cancer.

  • T3 – The cancer has begun to spread through the capsule that surrounds the prostate gland.

The T3 stage is divided into:

T3a – The tumour has broken through the capsule, but it is not affecting the surrounding structures.

T3b – The tumour has spread into the glands that produce semen (seminal vesicles). These are very close to the prostate gland and sit just underneath the bladder.

  • T4 – The tumour has started to spread into nearby parts of the body such as the bladder or rectum.

Prostate cancer T4
Prostate cancer T4

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T3 and T4 tumours are known as locally advanced prostate cancer because the cancer has started to spread outside the prostate gland and may be invading surrounding structures.

If the cancer has spread to other parts of the body, it’s known as metastatic, secondary, or advanced prostate cancer.

N stands for nodes

This describes whether there are any lymph nodes near the prostate gland that have cancer in them. The ‘N’ may have an ‘X’ or a number written next to it, which gives information about the nodes:

  • NX – The lymph nodes were not examined.
  • N0 – The lymph nodes were examined, but no cancer was found.
  • N1 – Cancer was found in the lymph nodes close to the prostate.

M stands for Metastasis

Metastasis means that the cancer has spread to other parts of the body, such as the bones.

The ‘M’ may have a number written next to it, which gives extra information about where the cancer has spread to:

  • M0 – The cancer has not spread to other parts of the body.
  • M1 – The cancer has spread to another part of the body, such as the bones, lung or liver.


Grading

The grade of a cancer gives an idea of how quickly it might grow. Prostate cancer is graded according to how the cancer cells look when the biopsy sample is looked at under the microscope.

The Gleason system is the most commonly used grading system. It looks at the pattern of cancer cells within the prostate. There are five patterns, which are graded from 1–5. 1 is very similar to normal prostate tissue, whereas 5 is very different to normal tissue. Only grades 3 to 5 are cancer.

All your biopsy samples are graded. The most common grade in the samples and the highest grade of the other samples are added together. This gives a Gleason score that ranges between 6–10.

Low-grade cancers with a Gleason score of 6 are usually slow-growing and less likely to spread. High-grade cancers  have a Gleason score of 8–10. They are more likely to grow quickly and to spread.

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