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Mesothelioma Staging Systems

Mesothelioma treatment options are usually based on the stage of mesothelioma a patient is in, or in other words, the extent to which a patient’s mesothelioma has progressed. There are three different staging systems for pleural mesothelioma, and each system takes into account somewhat different variables. Currently, there are no systems setting forth the stages of peritoneal mesothelioma or pericardial mesothelioma.

For all mesothelioma staging systems, the stages of mesothelioma are based on how tumors develop and spread. The staging systems have evolved over time and continue to change as scientists learn more about mesothelioma. Some elements common to most cancer staging systems are:

  • location of the primary tumor
  • size and number of tumors
  • lymph node involvement
  • cell type and tumor grade
  • metastasis (spread)

Stages of Mesothelioma Using the TNM System

The TNM staging system is a more recent system used to describe the stages of mesothelioma. This system takes into account tumor mass, lymph node involvement, and metastasis. The TNM system has four stages, which are:

  • Stage I: Malignant mesothelioma is in the left or right chest cavity (pleura), and may have spread to the lung, the sac around the heart (pericardium), or the diaphragm on the same side. At this stage, lymph nodes are not involved.
  • Stage II: At this stage, malignant mesothelioma has spread from one side of the pleura to lymph nodes near the lung on the same side. The mesothelioma may have also metastasized in the lung, pericardium, or diaphragm on the same side.
  • Stage III: Malignant mesothelioma has spread to the chest wall, muscle, ribs, heart, esophagus, or other organs in the chest on the same side as the initial tumor.
  • Stage IV: Malignant mesothelioma has spread to the chest lymph nodes on the opposite side of the original tumor, or extends to the pleura or lung on the opposite side, or directly extends to the abdominal cavity organs. Stage IV includes any distant metastasis.   

Other Systems that Describe Stages of Mesothelioma

In addition to the TNM system, two other systems are used to describe the stages of mesothelioma. First, the Butchart system is based mainly on the primary tumor’s mass and has four stages. Second, the Brigham system also has four stages, but bases its stages on lymph node involvement and whether the mesothelioma tumors can be removed. 

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