Prostate Cancer Grading and The Gleason Score Explained

When prostate cancer is graded, a system is used known as the Gleason Score to determine how aggressive the cancer is. The Gleason Score ranges from 1-5 and describes how much of the tissue taken from a biopsy looks like healthy tissue or abnormal tissue.

When you are diagnosed with cancer, you may find that the doctors looking after you may talk about your Gleason score and what the stage of your prostate cancer is. Your doctors will try and explain things in easily understood language, but some of the terminology used can be somewhat confusing. The following will help to explain the terminology and clarify any questions you may have. If you do not understand what your doctor is saying, tell them and ask for further clarification.

How The Gleason Score Is Determined

Pathologists grade prostate cancer using number from 1-5 based on what tissue looks like under a microscope. This grading system is what is known as The Gleason Score. Because prostate cancers often have areas with different grades, 2 grades are assigned to make up the majority of cells affected by the cancer. These 2 grades are added to yield the Gleason score. The highest a score can be is 10.

The first number that is assigned is the grade that is most common in the cancerous tumour. For example, if the score is written as 2+3, this means that the tumour is grade 2 and less is 3, which is added up to make a Gleason Score of 5. The higher that the score is, the most likely it is that the cancer will grow and spread more quickly than a lower score.

Grades 1 and 2 are not usually used for biopsies; the lowest score found on a biopsy is 6. These types of cancers are typically called low-grade and are likely to be less aggressive. Cancers that score 8-10 are considered high-grade. They are likely to grow and spread quickly. However, a cancer that scores 9-10 is twice as likely to grow and spread quickly as cancer with a score of 8 would.

Can The Gleason Score Really Tell The Cancer Grade for The Entire Prostate?

Biopsies are samples of tissues that are taken from different areas of the entire prostate. The Gleason Score that is determined following a biopsy reflects the cancer’s overall grade. In most cases, multiple biopsies are taken from the prostate to reduce the risk of over or underscoring.

TNM Staging

TNM staging is a system that is used by doctors to stage prostate cancer. Doctors use this information to determine what the best course of treatment is for a patient. The most suitable treatment option depends on the stage of the cancer, the severity of symptoms and a man’s general health status. TMN stands for Tumour, Node, Metastasis.

T – Tumour

Tumour (T) describes the size and extent of the area affected by the cancer (tumour). There are 4 stages of cancer stage in prostate cancer. This is T1 to T4.


T1 staging means that the cancerous cells are too small to be seen on a scan or felt during a prostate examination. T1 is divided into T1a, T1b and T1c.

  • T1a means the cancer consists of no more than 5% of the removed tissue.
  • T1b means the cancer of consists of more than 5% of the removed tissue.
  • T1c cancers are normally found following a biopsy, for example, after a raised PSA level has been discovered.


T2 staging means the cancer is entirely inside the prostate gland. T2 is divided into T2a, T2b and T2c.

  • T2a means the cancerous cells are only in half of one side of the prostate gland.
  • T2b means that the cancer is in more than half of one side of the prostate but has not grown and spread to the other side of the gland.
  • T2c means the cancer has affected both sides of the prostate gland. But, hasn’t spread to other parts of the body.


T3 staging means the cancer has broken through the covering of the prostate gland. T3 is divided into T3a and T3b.

  • T3a means the cancer has broken through the covering of the prostate which is known as the capsule.
  • T3b means the cancer has grown and spread to the seminal vesicles.


T4 means the cancer has grown and spread to other organs.

N – Node

Node (N) describes whether the cancer has spread to the lymph nodes. Lymph nodes are part of the immune system and are found throughout the body. The lymph nodes close to the prostate gland are a commonplace for prostate cancer to spread to. Symptoms depend on which lymph nodes are affected by the cancer. The most common is swollen lymph nodes. N is split into N0 and N1.

  • N0 means that the lymph nodes don’t contain cancerous cells.
  • N1 means there are cancerous cells in the lymph nodes.

M – Metastasis

Metastasis (M) means that the cancer has spread to other parts of the body from where it first started. M0 and M1 are the 2 stages of Metastasis.

  • M0 means the cancer hasn’t spread to other parts of the body.
  • M1 means the cancer has grown and spread to other parts of the body outside the pelvis. M1 is split into M1a, M1b and M1c.
  • M1a means there are cancerous cells in the lymph nodes that are outside of the pelvis area.
  • M1b means there are cancerous cells in the bone.
  • M1c means there are cancerous cells in other body parts or organs.


The Gleason Score helps a medical team decide the best course of treatment. But, the type of treatment will also depend on a few other things, including:

  • Age and general health status
  • PSA blood test levels
  • The type of cells that the cancer originated from
  • How a patient feels about the suggested treatment(s)
  • What the cells look like under a microscope

A patient might not receive treatment straight away. Sometimes a medical team like to monitor cancer and start treatment if it starts to grow or spread. If a patient does start to receive treatment, this can include:

  • Surgery to completely remove the prostate
  • Chemotherapy
  • Internal or external radiotherapy
  • Hormone therapy
  • Cryotherapy (Focal Ablation)
  • High Intensity Focal Ultrasound (Focal Ablation)

HIFU and Why Prost8UK Are Campaigning

At Prost8 UK, we strongly believe in promoting less invasive treatment options for men with early-stage non-metastatic prostate cancer, including Focal Ablation. The most common version of Focal Ablation is HIFU (high intensity focal ultrasound) which focuses sound waves to create a point of heat which destroys the cancerous cells with minimal damage to surrounding healthy tissue. We also campaign for earlier awareness of the symptoms through newer, simpler and more accurate prostate cancer screening. If you would like to support our very important cause and help us help all men in the UK, then please visit our donation page today.

Prostate Cancer Grading and The Gleason Score Explained

Written by Lloyd Parkinson. 

Endorsed by: 

Professor Hashim U. Ahmed PhD, FRCS(Urol), BM, BCh, BA(Hons) – Chair & Professor of Urology, Imperial College London. Chair, NCRI Prostate Research Group. 

Major Mark Vertue TD MBA, BSc Hons, Cert Ed, RN – Head of Department and Trustee & Clinical Director at Prost8 UK. 

Victor Griffin – Expert clinical application specialist of the HIFU system with Sonacare Medical Inc., supporting clinical trials in the UK and surgical teams internationally. 

Paul Sayer – CEO Prost8 UK and lead for the campaign to access less invasive treatment pathways for men with early stage prostate cancer. 

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