TNM System

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The TNM Classification of Malignant Tumors (TNM) is a cancer staging system devised by French surgeon and cancer researcher Dr. Pierre Denoix between 1943 and 1952. It is administered by the International Union Against Cancer (UICC) as the de facto global standard for classifying the extent and spread of cancer.

The American Joint Committee on Cancer (AJCC) has established a mesothelioma staging system based closely upon the TNM system for use in the United States.

In TNM mesothelioma staging, a special grouping procedure is used which classifies the progression of cancer using the size and local spread of the primary tumor (T), its impact upon the lymph nodes (N), and its level of metastasis, or spread through the body (M) as inputs. These stages are named using Roman numerals from I to IV.

  • Stage I: Mesothelioma involves the right or left pleura
  • Stage II: Mesothelioma has spread from the pleura on one side to areas on the same side
  • Stage III: Mesothelioma has spread into the chest wall muscle, ribs, and other organs on the same side as the primary tumor
  • Stage IV: Mesothelioma has spread into the lymph nodes in the chest on the side opposite that of the primary tumor, into other major organs, or spread to organs beyond the chest and/or abdomen