What are the Different Stages of Mesothelioma?

As is the case with most cancers, mesothelioma is diagnosed according to the stage the cancer is currently in. Stages are arranged in numerical order that ascends in conjunction with the severity of the malignancy. Typically, the later the stage, the farther the cancer has travelled beyond its point of origin within the body.

Mesothelioma is diagnosed as being a stage I, II, III, or IV cancer. There are three main staging systems in place for diagnostic purposes; however, doctors mainly use the TNM system when diagnosing mesothelioma. The stage of cancer is directly related to a patient’s prognosis.

The TNM Staging System

The letters in the title of the TNM staging system represent tumor, lymph node, and metastasis respectively. This is because doctors use this system to determine how big and how close to organs the patient’s tumor is, whether or not the malignancy has spread to the lymph nodes, and if the cancer has traveled to other organs or locations. The TNM system was developed by the American Joint Committee on Cancer.

What Occurs at Each Stage?

TNM Stage I

Localized mesothelioma is known as stage I. During the earliest stage, the cancer has not traveled outside of the mesothelium covering the lungs, heart, or abdomen depending on the point of origin. In stage I, mesothelioma may be treated effectively by surgical removal of the affected cells, plus some of the surrounding tissue. If the cancer is localized but is present in more than one area, then surgeons may perform a pleurectomy, or the removal of the lung’s surrounding membrane. In addition to surgery, chemotherapy may be used to further fight the return of the malignancy. Mesothelioma is rarely diagnosed during stage I due to the cancer’s long latency periods. A latency period is the time between the initial exposure and the onset of symptoms. Latency periods for mesothelioma are generally between 20 to 50 years according to the American Cancer Society.

TNM Stage II

Mesothelioma in stage II has traveled to the lungs and/or the diaphragm, but the lymph nodes have not yet been affected.


Stage III mesothelioma occurs when the cancer either moves into the lymph nodes or the abdomen lining or mediastinum. Along with the lymphatic system, mesothelioma can travel through blood vessels to other parts of the body and organs.

TNM Stage IV

A diagnosis of stage IV mesothelioma means that the cancer has spread to vital organs outside the point of origin, such as the brain or liver. The cancer could also be present in essential areas like the heart, spine, or esophagus. Unfortunately, this stage of cancer generally carries with it a poor patient prognosis. If diagnosed during the later stages, patients are usually given palliative treatments aimed at improving their quality of life and alleviating pain from symptoms. At this time curative measures are generally no longer an option.