Malignant Pleural Mesothelioma: Stages

What does the stage of a cancer mean?

The stage of a cancer is how much cancer there is and how far it has spread in your body. Your healthcare provider uses exams and tests to find out the size of the cancer and where it is. Scans can also show if the cancer has grown into nearby areas, and if it has spread to other parts of your body. The stage of a cancer is one of the most important things to know when deciding how to treat the cancer.

The place where cancer starts is called the primary site. Malignant pleural mesothelioma, or MPM, starts in the cells that make up the pleura. The pleura is a thin layer of tissue that lines the inside of the chest and covers the outside of the lungs. As MPM grows, it can spread from the primary site (the pleura) to nearby tissues and organs and, over time, to other parts of your body. Cancer that has spread is called metastatic cancer. When a cancer spreads, it’s said to have metastasized.

The TNM system for malignant pleural mesothelioma

At this time, malignant pleural mesothelioma (MPM) is the only type of mesothelioma that has a formal staging system. The other types of this cancer, including peritoneal mesothelioma (which starts in the lining in the abdomen) and pericardial mesothelioma (which starts in the lining around the heart), don’t have formal staging systems.

The most commonly used system to stage MPM is the TNM system from the American Joint Committee on Cancer. Be sure to ask your healthcare provider to explain the stage of your cancer to you in a way you can understand.

The first step in staging is to find the value for each part of the TNM system. Here's what the letters stand for in the TNM system:

• T tells how far the main tumor has spread into the pleura and other nearby structures.

• N tells if the lymph nodes near the primary tumor have cancer in them.

• M tells if the cancer has spread ( metastasized) to distant organs in the body, such as the liver, bones, the lung, or pleura on the other side of the body, or the lining of your belly or abdomen (called the peritoneum).

Numbers or letters after T, N, and M provide more details about each of these factors. There are also two other values that can be assigned:

• X means the provider does not have enough information to tell the extent of the main tumor (TX), or if the lymph nodes have cancer cells in them (NX).

• 0 means no sign of cancer, such as no sign of lymph node spread (N0).

What are the stage groupings of malignant pleural mesothelioma?

The T, N, and M values from the TNM system are used to put these cancers into stage groupings. These groupings give an overall description of your cancer. A stage grouping is listed as a Roman numeral and can have a value of I (1), II (2), III (3), and IV (4). The higher the number, the more advanced the cancer is.

These are the stage groupings of MPM and what they mean:

Stage I. The cancer has not spread to nearby lymph nodes or to other distant parts of the body. Surgery may be a treatment choice. This stage is divided into two groups:

• Stage IA. The cancer is in the pleura lining the chest wall on one side of the chest. It may or may not also be in the pleura covering the diaphragm (the breathing muscle that separates the chest from the abdomen), the mediastinum (the space between the lungs), or the lung on the same side.

• Stage IB. The cancer is in the pleura lining the chest wall on one side of the chest and in the pleura covering the diaphragm, the mediastinum, and the lung on the same side. It has spread into the diaphragm muscle and/or into the lung tissue. The cancer might also have spread to other nearby tissues, including at least one of these: the first layer of the chest wall, the deeper layers of the chest wall at only one spot, the fatty tissue between the lungs, or the pleura around the heart (the pericardium). But the cancer might still be able to be removed with surgery.

Stage II. The cancer is in the pleura lining the chest wall on one side of the chest. It may or may not have grown into the diaphragm muscle or the lung tissue on the same side. It has spread into the lymph nodes that drain the chest and the lung on the same side of the body. But it has not spread to distant parts of the body. Surgery may be a treatment choice.

Stage III. This stage is divided into two groups:

• Stage IIIA. The cancer has spread to nearby tissues, but it might still be able to be removed with surgery. It's in the pleura lining the chest wall on one side of the chest and in the pleura covering the diaphragm, the mediastinum, and the lung on the same side. It has also spread into the lymph nodes that drain the chest and the lung on the same side of the body, as well as at least one of these places: the first layer of the chest wall, the deeper layers of the chest wall at only one spot, the fatty tissue between the lungs, or the pleura around the heart (the pericardium). It has not spread to distant parts of the body.

• Stage IIIB. The cancer has not spread to distant parts of the body and is either of the following:

  • The cancer may or may not have spread to nearby tissues, and it might still be able to be removed with surgery. It has spread into lymph nodes on the other side of the body or to lymph nodes above the collar bone on either side of the body.

  • The cancer has spread too far to be removed with surgery. It's in the pleura lining of the chest wall on one side of the chest and in the pleura covering the diaphragm, the mediastinum, and the lung on the same side of the body. It has also spread to at least one of these places: more than one spot deeper into the chest wall, like to the muscles or ribs; through the diaphragm and into the pleura that covers the organs in the abdomen or belly (called the peritoneum); any organ in the space between the lungs, like the thymus gland, windpipe, esophagus, or blood vessels; the spine; across to the pleura on the other side of the chest; or through the pericardium and maybe into the heart muscle. It may or may not have spread to nearby lymph nodes.

Stage IV. The cancer may or may not have grown into nearby tissues and may or may not have spread to nearby lymph nodes. It has spread to distant parts of the body, such as the other side of the chest, the peritoneum, the liver, or bones.

Talking with your healthcare provider

Once your cancer is staged, talk with your healthcare provider about what the stage means for you. Ask any questions and talk about your concerns.