Staging

The stage of a cancer is a term used to describe its size and whether it has spread beyond the area of the body where it started. Knowing the extent of the cancer helps the doctors decide on the most appropriate treatment for you. There are a number of different staging systems. Many are based on the TNM system.

T describes the size of the cancer.

N describes whether the cancer has spread to the lymph nodes and which nodes are involved. For example, N0 means that no lymph nodes are affected, while N1 means there are cancer cells in the lymph nodes.

M describes whether the cancer has spread (metastasised) to another part of the body. For example, M0 means the cancer has not spread to other parts of the body, while M1 means the cancer has spread to other parts of the body.

Pleural mesothelioma

The staging system that’s most commonly used for pleural mesothelioma is called the International Mesothelioma Interest Group (IMIG) system. It’s based on the TNM system.

You may find it helpful to refer to the diagram showing the structure of the lungs and pleura while looking at the staging information.

Stage 1

Cancer cells are found in the pleura around the lung on one side of the chest.

  • Stage 1a Cancer cells are only found in the outer layer of the pleura (parietal pleura).
  • Stage 1b Cancer cells are also found in the inner layer of the pleura (visceral pleura).

Stage 2

The cancer has spread to both layers of the pleura and has either spread into the muscle of the diaphragm or into the lung tissue on one side of the chest.

Stage 3

The cancer has spread deeper into the tissues around the pleura. It may have spread to the:

  • chest wall
  • fatty tissue in the centre of the chest
  • tissue that separates the ribs from the pleura
  • outer lining of the heart (pericardium).

Or, it may have spread to local lymph nodes.

Stage 4

The cancer has spread deeply into the tissues close to the pleura. It may have spread to the:

  • pleura on the other side of the chest
  • diaphragm and the lining surrounding the abdomen (peritoneum)
  • spine
  • internal surface of the heart pericardium and into the muscle of the heart.

Or, it may have spread to the lymph nodes on the other side of the chest or the lymph nodes above the collarbone on the same or other side of the chest. Or, it may have spread to distant organs or tissues.

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