The stages of stomach cancer

The stage of a cancer tells the doctor the size of the tumour and whether it has spread. The tests and scans you have when diagnosing your cancer give some information about the stage. It is important because treatment is often decided according to the stage of a cancer. But your doctor may not be able to tell you the exact stage of cancer in your stomach until you have surgery.

There are different ways of staging cancers. The two main ways are the TNM system and the number system. There is more general information about staging cancers in the CancerHelp UK section about cancer.

'TNM' stands for Tumour, Node, Metastasis. The system describes

• The size and spread of the stomach tumour (T)
• Whether cancer cells have spread to lymph nodes (N)
• Whether the cancer has spread to a different part of the body (M)
  

The size and spread of the stomach tumour (T)

T1 means the tumour has started to grow into the wall of the stomach. T1 is further divided into T1a and T1b. T1a has grown no further than the connective tissue beneath the submucosa lining the stomach. And T1b has grown no further than the inner layer of the stomach (submucosa).

T2 means the tumour has grown into the muscle layer of the stomach wall.

T3 means the tumour has grown into the membrane covering the outside of the stomach.

T4 means the tumour has grown outside of the stomach wall.  It is further divided into T4a and T4b. T4a means the tumour has grown right through the stomach wall and broken through it. And T4b means it has grown through the stomach wall and into other organs or body structures nearby such as the liver, gullet, or abdominal wall. 

Whether cancer cells have spread to lymph nodes (N)

• N0 means that there are no lymph nodes containing cancer cells
• N1 means that there are cancer cells in 1 to 2 lymph nodes near to the stomach
• N2 means there are cancer cells in 3 to 6 nearby lymph nodes
• N3a means there are cancer cells in 7 to 15 nearby lymph nodes
• N3b means there are cancer cells in 16 or more nearby lymph nodes

Whether the cancer has spread to a different part of the body (M)

There are 2 M stages for stomach cancer

• M0 means the cancer has not spread to other organs
• M1 means the cancer has spread to other parts of the body

There are five main stages in this system - stages 0 to 4.

• Stage 0 or carcinoma in situ (CIS)
• Stage 1
• Stage 2
• Stage 3
• Stage 4

Stage 0 or carcinoma in situ (CIS)

If you are told you have CIS or stage 0 stomach cancer, you have a very early stage of stomach cancer. There are cancer cells in your stomach lining. But they are completely contained within the inner layer of the lining. So there is very little risk of any cancer cells having spread. It is not usual for stomach cancer to be diagnosed this early.

Stage 1

This is the earliest stage of cancer. It is divided into 1a and 1b.

Stage 1a means the cancer has grown no further than the lining of the stomach, with no cancer in the lymph nodes (T1, N0, M0).

Stage 1b means either that

• The cancer has still only just grown through the lining, but nearby lymph nodes contain cancer cells (T1, N1, M0) OR
• There are no cancer cells in the lymph nodes, but the cancer has grown into the muscle of the stomach wall (T2, N0, M0)

Stage 2

Stage 2 is also divided into a and b

Stage 2a means that 

• The cancer has only reached the lining of the stomach, but between 3 and 6 lymph nodes contain cancer cells (T1, N2, M0) OR
• The cancer has grown into the muscle layer of the stomach wall and is also in1 or 2 nearby lymph nodes (T2, N1, M0) OR
• The cancer has grown into the membrane covering the outside of the stomach but there are no cancer cells in the lymph nodes (T3, N0, M0)

Stage 2b means that 

• The cancer has only reached the lining of the stomach wall and 7 or more lymph nodes contain cancer cells (T1, N3, M0) OR
• The cancer has grown into the muscle layer of the stomach but between 3 and 6 lymph nodes contain cancer cells (T2, N2, M0) OR
• The cancer has grown into the membrane covering the outside of the stomach and is also in 1 or 2 nearby lymph nodes (T3, N1, M0) OR
• The cancer has grown outside of the stomach wall but there are no cancer cells in nearby lymph nodes (T4a, N0, M0)

Stage 3

Stage 3 is divided into a, b and c.

Stage 3a means that the cancer has grown

• Into the muscle layer of the stomach and 7 or more lymph nodes contain cancer cells (T2, N3, M0) OR
• Through the stomach wall, but between 3 and 6 nearby lymph nodes contain cancer cells (T3, N2, M0) OR
• Through the stomach wall and 1 to 2 nearby lymph nodes contain cancer cells (T4a, N1, M0)

In stage 3b the cancer has grown

• Into the membrane surrounding the outside of the stomach wall and more than 7 lymph nodes contain cancer cells (T3, N3, M0) OR
• Right through the stomach wall and between 3 and 6 lymph nodes contain cancer (T4a, N2, M0) OR
• Right through the stomach wall and into nearby tissues and lymph nodes contain cancer (T4b, N0 to 1, M0)

In stage 3c the cancer has 

• Grown right through the stomach wall and more than 7 lymph nodes contain cancer (T4a, N3, M0) OR
• Grown right through the stomach wall and into nearby tissues and organs and lymph nodes contain cancer (T4b, N1 to 2, M0)

Stage 4

Stage four stomach cancer means your cancer is advanced and has spread to other body organs through the lymphatic system (any T any N, M1)