TNM stands for tumour, node and metastasis. Find out how the TNM system is used to stage gallbladder cancer.

Systems of stages

The stage of a cancer tells you how big it is and whether it has spread. It helps your doctor decide which treatment you need.

Most doctors use a system of stages called TNM, or a system of number stages.

TNM stands for tumour, node and metastasis:

• T describes how deeply the tumour has grown into the gallbladder
• N describes whether there is cancer in the lymph nodes
• M describes whether the cancer has spread to any other part of the body

Layers of the gallbladder

The diagram below shows the layers of the gallbladder. Knowing about the layers helps you understand the different stages.

T stages - the size and spread of the tumour

There are 5 stages of tumour size. A very early stage tumour called Tis or carcinoma in situ and numbered stages T1 - T4. 

Carcinoma in situ and T1

Tis (carcinoma in situ) is the earliest possible stage of gallbladder cancer. The cancer cells are all inside the lining of the gallbladder wall. The cancer has not spread anywhere else in the body. Gallbladder cancers are rarely found this early. This is only likely if you have had your gallbladder removed for other reasons, such as gallstones.

T1 means the tumour has started to grow into the wall of the gallbladder. T1 is divided into 2 further groups, T1a and T1b.

T1a means that the cancer has grown into the connective tissue layer underneath the inner lining of the gallbladder wall.

T1b means that the cancer has started to grow into the muscle layer underneath this connective tissue layer.

T2

T2 means the cancer is still contained in the gallbladder but has grown through the main muscle layer of the wall into the connective tissue underneath. 

T3

T3 means the cancer's grown right through the gallbladder wall. It may have begun to grow into the liver or one other nearby organ such as the stomach, bowel or pancreas.

T4

T4 means the cancer has grown into one of the main blood vessels into the liver (the hepatic portal vein or hepatic artery). Or, it's grown into 2 or more organs outside of the liver.

N stages - whether cancer cells have spread to the lymph nodes

There are 3 main stages of lymph node involvement in cancer of the gallbladder.

N0 means there are no lymph nodes containing cancer cells.

N1 means there are cancer cells in one or more nearby lymph nodes (such as along the bile duct or the main blood vessels to the liver).

N2 means there are cancer cells in lymph nodes further away from the gallbladder.

M stages - whether the cancer has spread to a different part of the body (metastasis)

There are just 2 M stages of gallbladder cancer.

M0 means the cancer has not spread to organs or structures far away from the gallbladder.

M1 means the cancer has spread to another part of the body far away from the gallbladder, such as the brain or lungs. Your doctor might call this distant metastasis.

How TNM stages are used

Together the T, N and M stages give a complete description of the stage of your cancer.

For example, if you have a T3, N0, M0 cancer, you have a tumour that has grown through the wall of your gallbladder and it may have spread into a nearby organ or structure. But the lymph nodes are clear and there is no spread of the cancer to more distant parts of your body. Using this type of stage grouping, doctors may then give the cancer stage a number.

Treatment

The stage of your cancer helps your doctor to decide which treatment you need. Treatment also depends on:

• your type of cancer (the type of cells the cancer started in)
• where the cancer is 
• other health conditions that you have

The stage of the cancer and these other factors can also give an idea of your outlook (prognosis).

Surgery is the main treatment for gallbladder cancer. The main type of surgery used is called a cholecystectomy, which means having your gallbladder removed. You might also need a second operation to remove any lymph nodes that contain cancer cells.

Radiotherapy can be used alongside other treatments. And you might have chemotherapy treatment for gallbladder cancer that has come back, or which can’t be treated with surgery. Chemotherapy can also be used to relieve your symptoms and slow the growth of your cancer.