Stages of mesothelioma

Staging and mesothelioma

There isn’t a well used staging system for peritoneal mesothelioma. This is mesothelioma that starts in the tissue covering organs in your tummy (peritoneum). Sometimes the doctors may use the TNM (Tumour Node Metastasis) system used for pleural mesothelioma.

There are different systems for staging mesothelioma. In the UK, doctors tend to use the most recent American Joint Committee on Cancer (AJCC) system. This includes the:

• TNM (Tumour, Node, Metastasis) system

• number system

The tests you have to diagnose your mesothelioma help your doctor find out the stage.

TNM staging for mesothelioma

TNM stands for Tumour, Node, Metastasis.

Tumour (T)

Tumour describes the size of the tumour.

There are 4 T stages in mesothelioma – T1 to T4:      

T1 means mesothelioma cells are in the ​pleura​ lining the chest wall (parietal pleura) on one side of your chest. It might also be in other layers of the pleura lining your ​diaphragm​ (diaphragmatic pleura), lung (visceral pleura) or ​mediastinum​ (mediastinal pleura).

T2 means mesothelioma cells are in all layers of the pleura lining one side of your chest. It has started to spread into the diaphragm muscle or the lung tissue.

T3 means mesothelioma is in all layers of the pleura on one side of the body, and has started to spread into the:

• chest wall

• mediastinum

• surface of the outer covering of your heart (pericardium)

Surgery to completely remove the mesothelioma might still be possible.

T4  mesothelioma means mesothelioma is in all layers of the pleura on one side of the body, and has grown into:

• more than one place in the deep layers of your chest wall

• the lining around your tummy (peritoneum)

• organs in your chest such as the food pipe (oesophagus), wind pipe (trachea) or large blood vessels

• the pleura on the other side of your chest

• your spine

• the inner layer of the pericardium which covers your heart

Surgery to completely remove the mesothelioma is not possible.

Node (N)

Node in TNM means your ​lymph nodes​. These are a network of glands throughout the body, for example in your armpits, neck and groin. They drain away waste fluid, waste products and damaged cells, and contain cells that fight infection.

Mesothelioma cells can enter the ​lymphatic system​ and travel around the body.

There are 3 lymph node (N) stages in mesothelioma - N0 to N2:

N0 means there are no mesothelioma cells in any lymph nodes

N1 means there are mesothelioma cells in lymph nodes close to the lung, on the same side of your chest as the main mesothelioma.

N2 means mesothelioma has spread to lymph nodes close to the lung, but on the other side of your chest to your mesothelioma. Or to lymph nodes above your collar bone on either side of your body.

Metastasis (M)

​Metastasis​ describes whether the mesothelioma has spread to a different part of the body.

There are 2 metastases (M) stages:

M0 means your mesothelioma has not spread to other parts of the body

M1 means your mesothelioma has spread to other parts of the body 

Cancer that has spread to other areas of the body, such as the bones or liver, is called advanced or metastatic cancer.

Number stages

There is another staging system for mesothelioma. It has 4 main stages, numbered from stage 1 to stage 4. Stage 1 is the earliest cancer and stage 4 is the most advanced.

Stage 1

Mesothelioma cells are in the ​pleura​ around the lung on one side of your chest. It is split into 2 stages, 1A and 1B.

Stage 1A means mesothelioma cells are in the pleura lining the chest wall (parietal pleura) on one side of your chest. It might also be in the pleura lining your ​diaphragm, lung or ​mediastinum.

It hasn’t spread to any lymph nodes or to distant parts of your body.

In TNM staging, stage 1A is T1, N0, M0.

Stage 1B means mesothelioma cells are in all layers of the pleura lining one side of your chest. The mesothelioma has also started to grow into at least one of the following:

• the diaphragm muscle

• lung tissue

• the chest wall

• the mediastinum

• the surface of the outer covering layer of your heart (pericardium)

It has not spread to any lymph nodes or to distant body parts.

In TNM staging, stage 1B is:

• T2, N0, M0

• T3, N0, M0

Stage 2

Mesothelioma cells might be in all layers of the pleura lining one side of your chest. And it might have started to spread into the diaphragm muscle or lung tissue.

It has also spread to lymph nodes close to the lung, on the same side of your chest as the main cancer.

In TNM staging, stage 2 is:

• T1, N1, M0

• T2, N1, M0 

Stage 3

It might still be possible for the surgeon to remove stage 3 mesothelioma. Stage 3 is split into 2 stages, stage 3A and 3B.

Stage 3A means mesothelioma cells are in all layers of the pleura lining one side of your chest and has started to spread into one of the following:

• the chest wall

• the mediastinum

• the surface of the outer covering of your heart (pericardium)

There are mesothelioma cells in lymph nodes close to the lung on the same side of your chest as the main cancer.

In TNM staging, stage 3A is T3, N1, M0.

Stage 3B means mesothelioma cells might be in all layers of the pleura lining one side of your chest, and it might have started to grow into one of the following:

• the diaphragm muscle

• the lung tissue

• the chest wall

• the mediastinum

• the surface of the outer covering of your heart (pericardium)

The mesothelioma has spread to lymph nodes close to the lung, on the other side of your chest to the mesothelioma. Or to lymph nodes above your collar bone on either side of your body.

In TNM staging, stage 3B is:

• T1, N2, M0

• T2, N2, M0

• T3, N2, M0

Stage 4

Mesothelioma has spread to different parts of the chest wall, or it has grown:

• through the diaphragm into the lining around your tummy (peritoneum)

• into organs in your chest such as the food pipe (oesophagus) or wind pipe (trachea

• to the pleura on the other side of your chest

• to your spine

• into your heart

It may or may not have spread to your lymph nodes.

Or, stage 4 means mesothelioma has spread to other distant parts of your body.

In TNM staging, stage 4 is either:

• T4, any N, M0

• any T, any N, M1

Treatment

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

• your type of mesothelioma (the type of cells the cancer started in)

• how the cancer is likely to behave (the grade)

• other health conditions that you have

Find out about your treatment options for mesothelioma