Mesothelioma Stages: TNM Staging

The International Mesothelioma Interest Group’s TNM system for mesothelioma staging has been adopted by the American Joint Committee on Cancer (AJCC). This system, like most other cancer staging systems, uses a TNM-based classification, where:

T

T stands for tumor and the classification refers to its size and how far it has spread to nearby organs.

N

N stands for lymph nodes and the classification refers to the cancer having spread to regional or distant lymph nodes.

M

M is for metastasis and the classification refers to the cancer have spread (“metastasized”) to other organs.

In TNM staging, information about the tumor, lymph nodes, and metastasis is combined in a process called stage grouping to assign a stage described by Roman numerals from I to IV. This system has, for the most part, supplanted the Butchart system as the primary mesothelioma-staging system, although one will find some doctors still using Butchart.

TNM Staging System for Mesothelioma

Stage I

Mesothelioma involves either the right or left pleura lining the chest. It has only spread to the outer lining of the lung in, at most, a few small spots. It has not yet spread to the lymph nodes.

Stage II

Mesothelioma involves either the right or left pleura lining the chest and has spread from the lining of the chest into:

1. the outer lining of the lung; or
2. the diaphragm or; or
3. into the lung itself.
   
   

Stage III

Mesothelioma involves either the right or left pleura lining the chest and has spread into:

1. the first layer of the chest wall; or
2. the fatty part of the mediastinum; or
3. a single place in the chest wall; or
4. the outer covering layer of the heart; or
5. lymph nodes anywhere in the same side of the chest
   
   

Stage IV

Mesothelioma involves either the right or left pleura lining the chest and has spread:

1. into the chest wall, either muscle or ribs; or
2. through the diaphragm; or
3. into any organ contained in the mediastinum (esophagus, trachea, thymus, blood vessels); or
4. into the spine; or
5. across to the pleura on the other side of the chest; or
6. through the heart lining or into the heart itself; or
7. into the brachial plexus (nerves leading to the arm); or
8. into lymph nodes outside that side of the chest; or
9. spread to other organs through the bloodstream.