Staging and grading kidney cancer

After diagnosis, your doctors will need to find out the stage and the grade of the cancer. This will help them decide on the most appropriate treatment for you. The stage of a cancer describes its size and whether it has spread. The grade of a tumour describes the behaviour of cancer cells. It shows if they are slow- or fast-growing.

There are two main staging systems: the TNM system and the number staging system. 

Doctors use the TNM staging system to describe the stage of the cancer. This records information about how far the tumour has grown into the kidney and whether it has spread into nearby lymph nodes or distant organs. 

The number staging system shows how far the cancer may have spread on a scale of 1–4.

Doctors will also want to know the grade of the cancer. This will give them an idea of how quickly the cancer may grow. They will examine the cancer cells under a microscope and compare how they look to normal cells. If they look very different, the cancer may be a higher grade and so grow more quickly.

Staging and grading kidney cancer

The stage of a cancer describes its size and whether it has spread. Once your doctors know the stage of the cancer, they can plan your treatment.

The most commonly used staging system for kidney cancer is the TNM system:

  • T refers to the tumour size.
  • N refers to whether lymph nodes are affected.
  • M refers to whether the cancer has spread to other parts of the body (metastases).

T stands for tumour

  • T1 – The cancer is only in the kidney and is no larger than 7cm.
  • T1a – The cancer is no larger than 4cm.
  • T1b – The cancer is larger than 4cm but not larger than 7cm.
  • T2 – The cancer is larger than 7cm and is inside the kidney.
  • T3 – The cancer is growing into the fat around the kidney or into a major vein (the vena cava and renal vein) close to the kidney. But it is not growing beyond the outer covering of the kidney (capsule). See page 11 for an illustration of the kidney.
  • T4 – The cancer has spread outside the capsule that surrounds the kidney. It may have grown into the adrenal gland.

N stands for nodes

  • N0 – There are no cancer cells in any lymph nodes.
  • N1 – There are cancer cells in one or more lymph nodes.

If the cancer cells have spread to the lymph nodes, the nodes are said to be positive.

M stands for metastases

  • M0 – The cancer has not spread to other distant parts of the body.
  • M1 – The cancer has spread to distant parts of the body such as the bones, lungs, liver or brain. If the cancer has spread, it’s called secondary or metastatic kidney cancer.
  • The T, N and M stages may be grouped together to give a number stage for the cancer. These range from stages 1–4.


Number staging

Stage 1

  • The cancer is 7cm or less and is inside the kidney. There is no spread to the lymph nodes or other organs. This is the same as T1 N0 M0 in the TNM system.

Stage 2

  • The cancer is larger than 7cm and is inside the kidney. There is no spread to the lymph nodes or other organs. This is the same as T2 N0 M0 in the TNM system.

Stage 3

  • The cancer is growing into the fat around the kidney or into one of the major veins close to the kidney (the renal vein or the vena cava) but has not grown outside the capsule that surrounds the kidney. It has not spread to the lymph nodes. This is the same as T3 N0 M0 in the TNM system.
  • Or the cancer has spread to the lymph nodes but has not grown outside the capsule around the kidney. This is the same as T1–T3 N1 M0 in the TNM system.

Stage 4

  • The cancer has grown through the capsule that surrounds the kidney and may have grown into the adrenal gland. It may have spread to the lymph nodes. It has not spread to parts of the body far from the kidney. This is the same as T4 Any N M0 in the TNM system.
  • Or the cancer has spread to distant parts of the body. It can be any size and may have grown through the capsule surrounding the kidney and may have grown into the adrenal gland. It may have spread to the lymph nodes. This is the same as T1–T4 Any N M1 in the TNM system.


Grading

Grading refers to the appearance of the cancer cells under the microscope. The grade gives an idea of how the cancer may behave.

The Fuhrman system is the most common grading system for kidney cancer. It ranges from 1–4; the higher the number, the more abnormal the cells look. A grade 1 cancer is usually slow growing. It is less likely to spread than a higher grade, such as a grade 4 cancer.

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