Staging and grading of early prostate cancer

Your test results tell your doctors more about the size of the tumour and if it has spread outside the prostate. This is called the stage of the cancer. Doctors often use the TNM staging system. It gives information about the tumour, if it has spread to any lymph nodes, or to another part of the body (metastasis).

Early prostate cancer is contained to the prostate. It has not spread to lymph nodes or other parts of the body.

Early prostate cancer is also divided into risk groups. This looks at the T stage of the cancer, its grade and your PSA level. The grade tells how quickly the cancer cells may grow. The Gleason system is the most commonly used grading system. It looks at the patterns of the cancer cells in the prostate. There is also a newer system that grades the cancer between 1 and 5, depending on your Gleason score.

Risk groups are divided into low risk, intermediate and high risk. Knowing the stage and risk group of the cancer helps you and your doctors decide on the best treatment for you.

Staging of prostate cancer

The stage of a cancer describes its size and how far it has spread. The results of your tests help your doctors decide on the stage. You and your doctors can then talk about the best treatment choices for you.

Your doctors also look at the grade of the cancer and your PSA level (see below). This helps them to decide the risk group you are in to help plan your treatment.

Doctors often use the TNM staging system or a number staging system for prostate cancer.


TNM staging

This gives information about the tumour, if it has spread to any lymph nodes, or to another part of the body (metastasis). T is for tumour, N is for nodes, and M is metastasis.

Tumour

Doctors put a number next to the T to describe the size and spread of the cancer.

  • T1 means the tumour is contained in the prostate and is too small to be felt when a doctor does a rectal examination or seen on a scan. The cancer may have been diagnosed by a biopsy to check a raised PSA level. Or it may have been diagnosed by chance after an operation to remove part of the prostate to make peeing easier.
  • T2 means the tumour is still contained in the prostate, but your doctor can feel it when they do a rectal examination. T2 tumours are divided into:
    • T2a – The tumour is only in half of one of the two lobes of the prostate.
    • T2b – The tumour is in more than one half of one lobe.
    • T2c – The tumour is in both lobes.

T1 and T2 tumours have not spread to lymph nodes or other parts of the body. Doctors call this early or localised prostate cancer.

T3 and T4 tumours have started to spread outside the prostate and may be growing into tissues or organs close by. If the cancer has not spread to another part of the body, such as the bones, it is called locally advanced prostate cancer. When it has spread to another area, it is called advanced or metastatic prostate cancer.

T (tumour) stages of prostate cancer
T (tumour) stages of prostate cancer

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Nodes

N0 means there is no cancer in the lymph nodes near the prostate, so early prostate cancer is always N0.

Metastasis

M0 means the cancer has not spread to another part of the body, so early prostate cancer is always M0.

You can talk to your doctor or specialist nurse about your TNM staging. They can explain it to you.

The number staging system

This system brings together the different parts of the TNM staging system and gives it a number stage.

Early (localised) prostate cancer is either:

  • stage 1 when the cancer is very small
  • stage 2 when the cancer is a bit bigger.

It is contained to the prostate and has not spread outside it.


Grading of prostate cancer

A doctor decides the grade of the cancer by how the cancer cells look under the microscope. The grade gives an idea of how quickly the cancer might grow or spread.

Gleason score

Gleason is the most commonly used grading system. It looks at the pattern of cancer cells in the prostate. There are 5 different patterns, graded from 1 to 5.

Grade 1 is very similar to normal prostate tissue, and grade 5 is very different to normal tissue. Only grades 3, 4, and 5 are cancer.

There may be more than one grade. The doctor examines all the samples taken at your biopsy. They find:

  • the most common grade in the samples
  • the highest grade in the samples.

They add these together to get your Gleason score. A Gleason score of 7 could be 3 + 4 or 4 + 3.

If your Gleason score is between 6 and 10:

  • Gleason score 6 means the cancer is slow-growing and less likely to spread
  • Gleason score 7 means the cancer is between a slow-growing and fast-growing cancer (intermediate grade)
  • Gleason score 8 to 10 means the cancer is more likely to grow quickly and to spread (high grade).

Gleason grading system
Gleason grading system

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New grading system

This new system grades the cancer between 1 and 5, depending on your Gleason score. The lower the grade, the less likely the cancer is to spread. This helps your doctor to plan your treatment.

There are 5 Grade Groups:

  • Grade Group 1 (Gleason score 6) is the lowest grade and not likely to spread.
  • Grade Group 2 (Gleason score 3 + 4 = 7).
  • Grade Group 3 (Gleason score 4 + 3 = 7).
  • Grade Group 4 (Gleason score 8).
  • Grade Group 5 (Gleason scores 9 and 10).

This system splits Gleason score 3 + 4 and 4 + 3, although they both equal a score of 7. If your most common grade is 3 rather than 4, you are in Grade Group 2. Men in Grade Group 3 may need more treatment than men in Grade Group 2.

Gleason scores 8 to 10 are split into Grade Group 4 and Grade Group 5. Grade Group 5 cancers are more likely to spread quickly than Grade Group 4 cancers.


Prostate cancer risk groups

Early prostate cancer is also divided into risk groups. To work out your risk group, your doctor looks at the T stage of the cancer, your Gleason score and your PSA level. It helps you and your doctors decide on the best treatment choices for you.

Low-risk prostate cancers

Low-risk prostate cancers are usually a combination of the following:

  • Stage T1 to T2a
  • Gleason score of 6 and under
  • PSA level of 10 or under.

These cancers are unlikely to grow or spread for many years.

Intermediate-risk prostate cancers

Intermediate-risk prostate cancers are usually one of the following:

  • Stage T2b
  • Gleason score of 7
  • PSA level of 10 to 20.

These cancers are unlikely to grow for a few years.

High-risk prostate cancers

High-risk prostate cancers are usually one of the following:

  • Stage T2c
  • Gleason score of 8 to 10
  • PSA level of 20 or above.

These cancers are more likely to grow or spread in a few years.

Your doctor and specialist nurse can give you more information about your risk group.

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