Staging and grading of locally advanced 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).

Locally advanced prostate cancer has spread outside the prostate. It may be growing into tissue close by and has sometimes spread to nearby lymph nodes.

The number staging system brings together the different parts of TNM staging. Locally advanced prostate cancer is either stage 3 or sometimes stage 4.

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.

Knowing the stage and grade 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 to help them 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 for metastasis.

Tumour

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

  • T1 and T2 tumours are known as early (localised) prostate cancer. They are contained in the prostate.
  • T3 tumours have spread outside the prostate and may be growing into tissues close by. T3 tumours are divided into:
    • T3a – The tumour has spread through the capsule surrounding the prostate.
    • T3b – The tumour has spread to the seminal vesicles that produce some of the fluid for semen.
  • T4 tumours have spread into areas close by, such as the bladder or back passage (rectum), or the muscle that controls peeing.

Nodes

  • N0 means there is no cancer in the lymph nodes near the prostate.
  • N1 means there is cancer in 1 or more lymph nodes close by.

Metastasis

M0 means the cancer has not spread to another part of the body, so locally advanced 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. Locally advanced prostate cancer is either stage 3 or sometimes stage 4.

Stage 3 is any T3 tumour when the cancer has not spread to the lymph nodes or to another part of the body.

Stage 4 is any T4 tumour that either:

  • has not spread to the lymph nodes
  • has spread to the lymph nodes close by and is any size.

This is called locally advanced prostate cancer.

Stage 4 is also any tumour that has spread to another part of the body, such as the bones. This is called advanced or metastatic prostate cancer.


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.

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