Prostate cancer risk groups and the Cambridge Prognostic Group (CPG)

Doctors group prostate cancer into risk groups. Your risk group tells you how likely it is that the cancer will grow quickly or spread. This helps your doctor recommend if you need treatment and the type of treatment you need.

In the UK, doctors now divide localised and locally advanced prostate cancer into 5 risk groups. This is the Cambridge Prognostic Group (CPG). The 5 risk groups are from CPG1 to CPG5.

Some doctors may still use an older system that divides prostate cancer into 3 risk groups. These are:

• low risk prostate cancer 
• medium or intermediate risk prostate cancer  
• high risk prostate cancer   

The Cambridge Prognostic Group system

Doctors look at the results of your tests and scans to give you a score from 1 to 5. They look at the:

• Grade Group or Gleason score
• prostate specific antigen (PSA) level
• tumour stage. This is from the T stage from the TNM staging

Grade Groups

The Grade Groups tell you how much the cancer cells look like normal cells. A specialist doctor called a pathologist looks at several samples of cells from your prostate. These are biopsies.

They then grade each sample based on how quickly they are likely to grow and how aggressive the cells look.

PSA level

PSA is a protein made by both normal and cancerous prostate cells. A PSA level higher than what would be expected for someone of your age can be a sign of prostate cancer.

Tumour stage

The tumour stage describes the size of the tumour or area of the cancer. There are 4 main T stages of prostate cancer – T1 to T4.

This is a simplified description of the 4 T stages:

T1 means the cancer is too small to be seen on a scan or felt during an examination of the prostate.

T2 means the cancer is completely inside the prostate gland.

T3 means the cancer has broken through the capsule (covering) of the prostate gland.

T4 means the cancer has spread into other organs nearby such as the bladder.

The 5 Cambridge Prognostic Groups

Below is a description of the 5 CPG groups. Ask your doctor or specialist nurse if you have any questions about your CPG group.

Cambridge Prognostic Group 1 (CPG 1)

You have:

• a Gleason score of 6. This is Grade Group 1
• and a PSA level less than 10 nanograms per millilitre (ng/ml) 
• and a T stage of 1 or 2

Cambridge Prognostic Group 2 (CPG 2)

You have:

• a Gleason score of 3 + 4 = 7. This is Grade Group 2
• or a PSA level between 10 and 20 ng/ml
• and a T stage of 1 or 2

Cambridge Prognostic Group 3 (CPG 3)

You have:

• a Gleason score of 3 + 4 = 7. This is Grade Group 2
• and a PSA level between 10 and 20 ng/ml
• and a T stage of 1 or 2

Or

• a Gleason score 4 + 3 = 7. This is grade group 3
• and a T stage of 1 or 2

Cambridge Prognostic Group 4 (CPG 4)

You have one of the following:

• Gleason score of 8. This is Grade Group 4
• PSA level higher than 20 ng/ml
• T stage of 3

Cambridge Prognostic Group 5 (CPG 5)

You have two or more of the following:

• Gleason score 8. This is Grade Group 4
• PSA level higher than 20 ng/ml
• T stage of 3

Or

• Gleason score 9 to 10. This is Grade Group 5

Or

• T stage of 4

The 3 risk groups system

Some doctors may still use an older system that divides prostate cancer into 3 risk groups. But the National Institute for Health and Care Excellence (NICE) now recommends the CPG system instead. This is because research has found that the CPG is a more accurate way to assess prostate cancer.

NICE is an independent organisation that provides guidance to the NHS in England to improve healthcare.

Ask your doctor if you aren’t sure about your stage, Gleason score and PSA level or if you have questions about your risk group. 

Low risk prostate cancer is similar to CPG 1.

Medium or intermediate risk prostate cancer is similar to CPG 2 and CPG 3.

High risk prostate cancer is similar to CPG 4 and CPG 5. 

Treatment

Your CPG helps your doctor recommend if you need treatment and the type of treatment you need. Treatment also depends on:

• your age and general health
• how you feel about the treatments and side effects

You might not have treatment straight away if you are in the CPG 1, 2 or 3. Sometimes your doctor monitors your cancer and only starts treatment if the cancer begins to grow. Depending on your situation, they may call this:

• active surveillance
• watchful waiting

Your doctor might recommend you have treatment if you are in the CPG 2, 3, 4 or 5. Treatment might include:

• surgery to remove your prostate (prostatectomy)
• 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