Cancer staging and grading describes the size of the tumour, whether it has spread, and how it might behave. Cancer staging and grading is important because it helps to determine the best way to treat your type of cancer.
If you’re diagnosed with cancer, your doctor or surgeon will try to find out the size of your tumour, how far it has spread and the speed at which it may grow. This is called staging and grading.
Staging is important because it helps your specialist decide what the best treatment is for you, as well as determining the likely course of your cancer. Grading cancer cells is looking at how much they are like a normal cell under a microscope.
Staging is used by doctors and surgeons to describe the size of your tumour and how far it may have spread within your body.
The most commonly used method to describe cancers worldwide is called the TNM staging system. Not all cancers are staged using this system, so depending on the type of cancer you have you may see other staging systems used to describe your cancer. Ask your doctor or surgeon to explain these to you.
The TNM system describes the size of your original (primary) tumour (T), whether any cancer cells have spread from your primary tumour and have reached nearby lymph nodes (N), and whether the cancer cells have spread further around your body (M). Each stage has numbers that are used to categorise your cancer more specifically.
The TNM staging system is used to describe most types of cancer.
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 tumour.
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.
Your doctor or surgeon will rate your cancer according to whether or not it has spread to any nearby lymph nodes.
M in TNM staging
The M in the TNM staging system stands for metastases (cancer has spread to other parts of your body). Your doctor or surgeon will rate your cancer according to whether it has spread or not.
If you need more information about the stage of your cancer or what it means, ask your doctor or surgeon.
The TNM system is combined with a number stage. The number system uses numbers ranging from one to four.
The higher the number, the more your cancer is likely to have spread in your body. For example, Stage 1 means it’s a small tumour that hasn't spread to your lymph nodes (early stage cancer) and Stage 4 means the tumour has spread to other parts of your body (advanced cancer). Sometimes Stage 0 is used to describe a cancer (eg skin cancer), this means cancer is present but only in one small area and hasn’t spread yet.
The Dukes staging system is a lettered (A-D) system. It may be used to describe bowel cancer. However, the TNM system is gradually replacing Dukes letters.
Sometimes, the Gleason scoring system is used to grade prostate cancer. It depends on what your cancer cells look like under the microscope. The lower the Gleason score, the lower the grade of the cancer.
The cancer cells are graded one to five, according to the pattern of cells under the microscope which relates to how fast the cancer cells are growing (one being slow growing and five fast growing). The two most commonly occurring pattern numbers are added together to get the Gleason score, which can be from two to 10. The lower the Gleason score, the lower the grade of the cancer. A grade of six (or below) means you have a low grade cancer, which is less likely to spread.
Grading is used to describe what your tumour looks like under a microscope to get an idea of how it may progress. A low grade cancer cell looks most like a normal cell and is likely to grow more slowly. A high grade cancer cell looks abnormal and is more likely to spread.
If you have cancer, your surgeon 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 try and find out the speed at which your tumour may grow and how aggressive it is. There are three grades used to rate cancer.
If you have a high grade cancer, you may need different treatment than if you have a low grade cancer. Even when the grade doesn’t change a cancer’s stage, it may still affect your treatment.
If you’re unsure about how your cancer may be graded or need more information, ask your doctor or surgeon.
Produced by Stephanie Hughes, Bupa Health Information Team, September 2012.
For answers to frequently asked questions on this topic, see FAQs.
For sources and links to further information, see Resources.
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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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