Butchart system extent of primary tumor mass

* Stage I: Mesothelioma is present in the right or left pleura and may also involve the diaphragm on the same side.


* Stage II: Mesothelioma invades the chest wall or involves the esophagus, heart, or pleura on both sides. Lymph nodes in the chest may also be involved.


* Stage III: Mesothelioma has penetrated through the diaphragm into the lining of the abdominal cavity or peritoneum. Lymph nodes beyond those in the chest may also be involved.


* Stage IV: There is evidence of metastasis or spread through the bloodstream to other organs.

The more recent TNM system considers variables of tumor in mass and spread, lymph node involvement, and metastasis.