The most commonly used staging system for pleural mesothelioma is called the Tumor-Node-Metastasis (TNM) system. This system classifies cases of mesothelioma into one of four stages based on how big the tumors are, if they’ve spread into lymph nodes, and if they’ve metastasized or not.
The TNM staging system has been in use since 1996 after it was created by the International Mesothelioma Interest Group.