Malignant Pleural Mesothelioma: Stages

What does the stage of a cancer mean?

The stage of a cancer is how much and how far the cancer has spread in your body. Your healthcare provider uses exams and tests to find out the size of the cancer and where it is. He or she can also see if the cancer has spread to 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. MPM can spread from the primary site to other parts of your body. Cancer that has spread is called metastatic cancer. When a cancer spreads, it’s said to have metastasized.

Mesothelioma in the chest (malignant pleural mesothelioma or MPM) starts in the cells that line ithe nside of the chest or the lining covering the outside of the lungs. As MPM grows, it can spread into nearby tissues and organs. And, like all cancers, it can spread (metastasize) to other parts of the body.

The TNM system for malignant pleural mesothelioma

At this time, MPM is the only type that has a formal staging system. The other types of this cancer, including peritoneal mesothelioma (which starts in the abdomen), 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 (AJCC). 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 nearby tissue.

• N tells if the lymph nodes in the area of the original 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? 

Stage groupings are determined by combining the T, N, and M values from the TNM system. 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 through IV (1 through 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 lymph nodes or to distant parts of the body. 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 lining the diaphragm (the breathing muscle that separates the chest from the abdomen), the mediastinum (the space between the lungs), or the pleura covering the lung.

• Stage IB. The cancer is in the pleura lining the chest wall on one side of the chest and in the pleura lining the diaphragm, the mediastinum, and the pleura covering the lung on the same side of the body. It has also spread to the diaphragm or the lung. Or, the cancer has spread to nearby tissues, including at least one of these: the deeper layers of the chest wall at 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 and may or may not have grown into the diaphragm or the lung. It has spread into the lymph nodes that drain the chest and the lung on the same side of the body, but has not spread to distant parts of the body.

Stage III. This stage is divided into two groups:

• Stage IIIA. The cancer has spread to nearby tissues, but 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 lining the diaphragm, the mediastinum, and the pleura covering the lung on the same side of the body. 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 deeper layers of the chest wall at 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 these:

  • The cancer may or may not have spread to nearby tissues, but 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 the chest wall on one side of the chest and in the pleura lining the diaphragm, the mediastinum, and the pleura covering 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 diaphrgam and into the pleura that encloses 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 muscles. 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 the lung or pleura on the other side of the chest or to the peritoneum. It has also spread to other parts of the body, like 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. Make sure to ask questions and talk about your concerns.