The stage of a cancer describes how far the cancer has grown from where it started, and whether it has spread anywhere else.
Knowing the stage is important. It affects the decisions you and your doctors make about the treatment you have.
It’s only possible to tell the exact stage of stomach cancer after an operation to remove it. There are two staging systems.
TNM staging system
The most commonly used staging system for stomach cancer is the TNM staging system.
T refers to the size and spread of the tumour:
- T1 – the tumour has grown into the inner wall (mucosa or submucosa) of the stomach
- T2 – the tumour has grown into the muscle layer of the stomach
- T3 – the tumour has grown into the outer lining of the stomach
- T4 – the tumour has grown through the outer lining of the stomach.
N refers to whether nearby lymph nodes have cancer cells in them:
- N0 – no lymph nodes contain cancer cells
- N1 – cancer cells are in 1 to 2 nearby lymph nodes
- N2 – cancer cells are in 3 to 6 nearby lymph nodes
- N3 – cancer cells are in 7 or more nearby lymph nodes.
M refers to whether the cancer has spread to other parts of the body (secondary or metastatic cancer):
- M0 – the cancer has not spread
- M1 – the cancer has spread to other parts of the body.
Number staging system
This is a different staging system that has just four stages. These can be described as follows:
The cancer is in the lining of the stomach (mucosa) and may have reached the muscle layer. Between 0 to 3 lymph nodes may be involved.
The cancer is contained within the stomach wall and up to 6 lymph nodes are involved, or the cancer has grown through the stomach wall but no lymph nodes or other organs are involved.
Doctors sometimes call stages 1 and 2 early stomach cancer.
The cancer is contained within the stomach wall and more than 6 lymph nodes are involved. Or the cancer has grown through the stomach wall and up to 6 lymph nodes are involved.
Doctors call stage 3 locally advanced stomach cancer.
The cancer has spread outside the stomach to other parts of the body, such as the lungs, liver or the bones.
Doctors usually call stage 4 advanced or metastatic stomach cancer.