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Cancer staging and grading

Key points

  • Staging is used to describe the size of your tumour and whether it’s spread to other parts of your body.
  • Grading is used to describe what your tumour looks like under a microscope and how it may progress.
  • Cancer staging and grading is important because it can help determine the best way to treat your cancer.

 

Cancer is an abnormal and uncontrolled growth of cells which multiply to form a tumour. They can either be benign or malignant. Benign tumours are not cancerous, but malignant tumours are.

How cancer develops

Cancer staging and grading describes the size of your tumour, whether it has spread and how it might behave. It’s an important part of helping your doctor understand more about your cancer and how to treat it.

About cancer staging and grading

If you’re diagnosed with cancer, your doctor will try to find out:

  • the size of your tumour
  • how far your tumour has spread
  • the speed at which your tumour may grow

This is called staging and grading. Staging is important because it helps your doctor decide what might be the best treatment for you. It also helps your doctor determine the likely course of your cancer. Grading your cancer cells will involve your doctor looking at how much they look like normal cells under a microscope.

Cancer staging

Staging may be used by your doctor to describe the size of your tumour and how far it has spread within your body.

A commonly used method to describe cancers is the TNM staging system. However, not all cancers are staged using this method. Depending on the type of cancer you have your doctor may use other staging systems to describe your cancer. Ask your doctor to explain these to you.

TNM staging system

The TNM system describes:

  • the size of your original (primary) tumour and if it has grown into any of your nearby tissues
  • whether any cancer cells have spread from your primary tumour to nearby lymph nodes
  • if there are any metastases (when cancer spreads to other parts of your body)

Each stage has numbers and letters that are used to categorise your cancer more specifically.

T in TNM staging
The T in the TNM system stands for tumour. This part of the staging system generally describes the size or growth of your original tumour.

  • TX may be used if your tumour can’t be evaluated.
  • T0 means there is no evidence of a tumour.
  • Tis or Cis (tumour or cancer in situ) means your tumour is in one small area, usually in the uppermost layer of tissue and hasn’t spread yet.
  • T1 to T4 refer to the size of your tumour and how much it has spread into your nearby tissues. The higher the number, the larger your tumour and the more likely it has grown into your nearby tissues.

N in TNM staging
The N in the TNM system stands for lymph nodes. Your lymph nodes are glands throughout your body that are part of your immune system. This part of staging describes whether or not your cancer has spread to any nearby lymph nodes.

  • NX may be used if your lymph nodes can’t be evaluated.
  • N0 means there are no cancer cells in your lymph nodes.
  • N1 to N3 refer to either how many lymph nodes your cancer has spread to or the position of the nodes in relation to your primary tumour. The higher the number, the more lymph nodes may be affected.

M in TNM staging
The M in the TNM staging system stands for metastasis. It describes whether or not your cancer has spread to other parts of your body.

  • MX may be used if metastasis can’t be evaluated.
  • M0 means your cancer has not spread to any other parts of your body.
  • M1 means your cancer has spread away from your primary tumour and into one or more other areas of your body.

It’s important to remember that the numbers and letters for each type of cancer don’t mean the same thing. The TNM combinations correspond to four stages. When your doctor has worked out T, N and M of your cancer they will combine them to get an overall stage of your cancer.

It can be a bit confusing because across different forms of cancer, the same TNM code can indicate a different stage of cancer. So, as an example, if you have colon cancer and your  TNM is T3 N0 M0, your cancer will be at stage two. However, this combination corresponds to stage three in bladder cancer. Ask your doctor to explain anything you’re unsure about.

Dukes staging system

The Dukes staging system is a lettered (A-D) system and may be used to describe bowel cancer.

  • Dukes A means your tumour is contained within the wall of your bowel.
  • Dukes B means your tumour has grown into the muscle of your bowel wall.
  • Dukes C means one or more of your lymph nodes near your bowel are affected.
  • Dukes D means your original tumour has spread to other parts of your body.

Doctors may talk about the Dukes staging system, but it’s worth knowing that it’s an older system. If your doctor uses the Dukes staging system, you may want to ask if it can be translated into the TNM staging system. This is because it’s gradually being replaced by the TNM staging system as it provides more information about your cancer.

TNM and Dukes are the main staging systems, but other cancers, such as those that affect your blood or brain are staged differently.

Cancer grading

Grading is used to describe what your tumour looks like under a microscope so your doctor can get an idea of how it may progress. A low grade cancer cell looks like a normal cell and is likely to grow more slowly. A high grade cancer cell looks abnormal and is more likely to grow and spread faster.

If you have cancer, your doctor will take a sample of cells from your tumour (a biopsy) to send to a laboratory for testing. The cancerous cells will be looked at under a microscope to see how your tumour may grow.

There are four grades used to rate cancer. These are described below.

  • Grade 1 or low grade cancer is slow growing. The cancer cells look very much like healthy cells in your body.
  • Grade 2 or intermediate grade cancer grows slightly faster. The cancer cells look different from healthy cells in your body.
  • Grade 3/4 or high grade cancer is fast growing. The cancer cells look very different from healthy cells in your body.

If you have a high grade cancer, you may need different treatment than if you have a low grade cancer. Even though the grade doesn’t change a cancer’s stage, it may still affect your treatment.

The most common types of cancer that have their own grading systems include prostate cancer and breast cancer. These grading systems are described below.

If you’re unsure about how your cancer may be graded or need more information, ask your doctor.

Gleason scoring system

The Gleason scoring system is used to grade prostate cancer.

Your cancer cells are graded one to five, according to the pattern of cells under the microscope. Grade one cells look like normal prostate cells, whereas grade five cells look very different to normal prostate cells. A Gleason score is worked out by adding together the most common grade and the highest grade of what is left in your sample.

Your combined Gleason score will normally be six or higher. It’s rare to get a score lower than six as grade one and two are not cancer.

Nottingham grading system

The Nottingham grading system is used to grade breast cancer based on:

  • if your tumour has any normal structures within it
  • the size and shape of your tumour
  • how fast your tumour is growing

These three factors each get a score between one and three. The scores are then added together to give you a total score between three and nine. From this, three grades are possible.

  • Low grade – a score between three and five.
  • Intermediate grade – a score between six and seven.
  • High grade – a score between eight and nine.

Reviewed by Kuljeet Battoo, Bupa Health Information Team, June 2014.

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  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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