The stage of gallbladder cancer means how big the cancer is and whether it has spread. The grade means how abnormal the cancer cells look under a microscope. Your doctor uses this information to decide which treatment you need.
The staging system most often used for gallbladder cancer is the TNM staging system.
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 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.
T2 is divided into 2 further groups T2a and T2b.
T2a means the cancer has grown through the muscle layer into the connective tissue on the side of the gallbladder that is not near the liver. This is the side near the peritoneum.
T2b means the cancer has grown through the muscle layer into the connective tissue on the side near the liver. It has not spread to the liver.
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 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 to three nearby lymph nodes (such as along the bile duct or the main blood vessels to the liver).
N2 means there are cancer cells in four or more nearby lymph nodes.
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.
There is another staging system called the number staging system. There are four main stages - numbered 1 to 4. Some doctors also refer to stage 0.
Stage 0 or carcinoma in situ (CIS)
Very, very early stage gallbladder cancer is called CIS or stage 0. There are cancer cells only in the layer of tissue lining your gallbladder.
Some doctors may not regard this as a true cancer because the cancer cells are just in the lining. So there is very little risk of the cancer having spread.
It is unusual for gallbladder cancer to be found this early, as there are few or no symptoms at this stage. Sometimes it can be picked up this early when someone has their gallbladder removed for gallstones.
This is the earliest stage of invasive cancer. It means that the cancer is only in the inner layers of the tissues lining the gallbladder. It has not spread to nearby tissues, lymph nodes or other organs. Stage 1 is the same as T1, N0, M0 in the TNM stages.
This means that cancer has grown through the muscle layer of the gallbladder wall and into the connective tissue underneath. It has not spread outside the gallbladder. Stage 2 in the TNM stages is the same as T2, N0, M0.
This stage is divided into 3A and 3B.
Stage 3A means the cancer has grown through the gallbladder wall but has not spread to the lymph nodes (this is the same as TNM stages T3, N0, M0)
Stage 3B means the cancer is within the gallbladder wall or has broken through the outer lining and spread to nearby lymph nodes (this is the same as T1, T2 or T3, N1 or M0)
This means that the cancer is advanced. It's divided into stage 4A and 4B.
Stage 4A means the cancer has either grown into one of the main blood vessels leading into the liver, or into 2 or more organs outside of the liver. It might also have spread into nearby lymph nodes. This is the same as T4, N0 or N1, M0.
Stage 4B means the cancer is any size and:
- has spread to lymph nodes further away from the gallbladder. But has not spread to distant organs in the body. This is also known as any T, N2, M0.
- has spread to structures or organs far away from the gallbladder. This is also known as any T, any N, M1.
Grades of gallbladder cancer
The grade of a cancer is a way of measuring how abnormal cancer cells are compared to healthy cells. It also gives an idea of how quickly a cancer may grow and whether it is likely to spread.
Low grade cancers are usually slower growing and less likely to spread. High grade cancers tend to be faster growing and more likely to spread.
There are 3 grades of gallbladder cancer – grade 1 to grade 3:
This means the cancer cells look similar to normal gallbladder cells. This is called low grade or well differentiated cancer.
This means the cancer cells look a bit abnormal. This is called intermediate grade cancer.
This means the cancer cells look very abnormal and unlike normal gallbladder cells. This is called high grade or poorly differentiated cancer.
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).
If you can have surgery, the main type of surgery is a cholecystectomy. This means having your gallbladder removed. You might also need a second operation. This might be to remove:
- any lymph nodes that contain cancer cells
- a small part of the liver where the gallbladder used to be attached
Radiotherapy can be used alongside other treatments. You might have chemotherapy or immunotherapy for gallbladder cancer that has come back, or which can’t be treated with surgery. These treatments can also relieve your symptoms and slow the growth of your cancer.