Staging, grading and risk groups for prostate cancer

Knowing the stage, grade and risk group of the cancer helps your doctors plan the best treatment. Gleason is the most commonly used grading system for prostate cancer. Early prostate cancer is also divided into risk groups.

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.

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

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TNM staging system

This gives information about:

  • the tumour (T)
  • whether the cancer has spread to any lymph nodes (N)
  • whether the cancer has spread to another part of the body, called metastasis (M).

Tumour

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

  • T1 – the tumour is contained in the prostate. It is too small to be felt on a rectal examination or seen on a scan. It may have been diagnosed by a biopsy for a raised PSA level. Or, it may have been diagnosed by chance after surgery to remove part of the prostate to make peeing (passing urine) easier.
  • T2 – the tumour is still contained in the prostate. But it can be felt when the doctor does a rectal examination or is seen on a scan. T2 tumours are divided into:
  • T2a – the tumour is only in half of 1 of the 2 lobes of the prostate
  • T2b – it is in more than half of 1 lobe
  • T2c – it is in both lobes.

T1 and T2 tumours are not likely to affect the lymph nodes or to spread. Doctors call this early or localised prostate cancer.

  • T3 tumours have spread outside the prostate and may be growing into tissues close by:
    • T3a – the tumour has spread through the capsule surrounding the prostate.
    • T3b – the tumour has spread to the seminal vesicles that produce 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 (passing urine).

T3 and T4 cancers are called locally advanced prostate cancer.

When the cancer has spread to another area, it is called advanced or metastatic prostate cancer.

Nodes

Metastasis

  • M0 means the cancer has not spread to another part of the body, so locally advanced prostate cancer is always M0.
  • M1 means the cancer has spread to another part of the body, so advanced prostate cancer is always M1.

With the TNM staging system, advanced or metastatic prostate cancer can be any T, any N, and always M1.

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

Number staging system

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

  • Stage 1
    The tumour is contained in the prostate.
  • Stage 2
    The tumour is bigger but still contained to the prostate.
  • Stage 3
    The tumour has started to break through the outer capsule of the prostate and may be in the nearby tubes that produce semen (seminal vesicles).
  • Stage 4
    The tumour has spread outside the prostate. It may have spread to areas such as the bladder or back passage (rectum). Or it may have spread further, for example to the bones.

Using the numbered staging system described above:

Grading prostate cancer

A doctor decides the grade of the cancer by how the cancer cells look under the microscope. This information comes from your biopsy results.

The grade gives an idea of how quickly the cancer might grow or spread. Doctors use a combination of 2 systems to grade the cancer. These are called:

  • Gleason score
  • Grade Group.

Gleason score

Gleason is a commonly used grading system for prostate cancer. The Gleason score examines the pattern of cancer cells in the prostate tissue, and how they look and act, compared with normal cells.

There are 5 different patterns, graded from 1 to 5. Grade 1 and 2 looks like normal prostate tissue. But grade 5 is very different to normal tissue.

There may be more than 1 grade. The doctor examines all the biopsy samples taken and decides on:

  • the most common grade
  • the highest grade.

They add these together to give your Gleason score. A Gleason score of 7 could be:

  • 3 + 4 – The most common grade is 3 and the highest grade is 4.

Or:

  • 4 + 3 – The most common and highest grade are both 4, but there is also some grade 3 present.

What your Gleason score means

If your Gleason score is between 6 and 10, the cancer is:

  • Gleason score 6 – slow-growing
  • Gleason score 7 – intermediate-grade (between slow and fast-growing)
  • Gleason score 8 to 10 – high-grade (more likely to grow quickly).

Grade Group

This grades the cancer between 1 and 5 based on your Gleason score. The lower the Grade Group, the less likely the cancer is to grow and spread.

There are 5 Grade Groups:

  • Group 1 – Gleason score 6
  • Group 2 – Gleason score 7 (3+4)
  • Group 3 – Gleason score 7 (4+3)
  • Group 4 – Gleason score 8
  • Group 5 – Gleason score 9 to 10.

If you are in Group 3, where the highest grade is most common, you may need more treatment than Group 2.

Risk groups for prostate cancer

Early prostate cancer is divided into risk groups.

Before planning your treatment, your cancer doctor will look closely at your risk group. This helps you and your doctors to decide on the best treatment for you. The treatment options for each risk group can be different.

To work out your risk group, your doctors look at:

  • your PSA level
  • your Gleason score – the pattern of the prostate cells and how they compare with normal prostate cells
  • the stage of the cancer – the size of the tumour and how far it has spread.

Low-risk prostate cancers

Low-risk prostate cancer has all of the following:

  • a PSA level of under 10
  • a Gleason score of 6 or under
  • is stage T1 to T2a.

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

Intermediate-risk prostate cancers

Intermediate-risk prostate cancer has any of the following:

  • a PSA level 10 to 20
  • a Gleason score of 7 or under
  • is stage T2b.

These cancers are unlikely to grow for a few years.

High-risk prostate cancers

High-risk prostate cancer has any of the following:

  • a PSA level that is higher than 20 or over 20
  • a Gleason score of 8 to 10
  • is stage T2c or more.

High-risk cancers are more likely than the other risk groups to grow or spread in a few years. They are more likely to be locally advanced prostate cancer. Your doctor and specialist nurse can give you more information about your risk group.

Some cancers that are contained in the prostate gland are described as locally advanced.

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