Medical professionals currently use three different mesothelioma-staging systems to diagnose and treat pleural mesothelioma. Each system measures different variables including the extent of the cancer, lymph node involvement, metastasis, and more.
1. Butchart System is the oldest and most commonly used mesothelioma cancer staging system and is primarily based on the extent of the tumor mass. Butchart System divides mesothelioma into four stages:
- Stage I – Mesothelioma cancer is seen in the right or left side of the chest area, or pleura cavity, and may also be found in the diaphragm.
- Stage II – Mesothelioma cancer has invaded the chest lining and reaches the esophagus, heart, or pleura on both sides. Lymph nodes may also be affected.
- Stage III – Mesothelioma cancer has passed the diaphragm and entered the abdominal cavity or peritoneum. Lymph nodes beyond the chest may also be affected.
- Stage IV – Mesothelioma cancer has spread through the bloodstream to other organs
2. TNM System is a more recent system used to stage mesothelioma by considering variables such as the tumor size and spread, lymph node involvement, and metastasis. In the TNM system, the disease is divided into four stages:
- Stage I – Mesothelioma cancer is in the right or left chest cavity and may have spread to the pericardium, diaphragm, or lung on the same side. Lymph nodes are not affected.
- Stage II – Mesothelioma cancer has spread from one side of the chest to a lymph node near the lung on the same side. The disease may have also spread to the lung, diaphragm, or pericardium on the same side.
- Stage III – Mesothelioma cancer has entered the chest wall, muscle, heart, esophagus, ribs, and vital organs in the pleural cavity on the same side. Lymph nodes may or may not be affected on the side of the tumor.
- Stage IV – Mesothelioma cancer has spread to the lymph nodes in the chest area on the other side of the tumor, or has spread to the pleural cavity or lung on the other side, or has reached organs in the abdominal area or neck. Any metastasis is involved in the fourth stage.
3. Brigham System is the latest mesothelioma cancer staging system and is based on tumor resectability (ability to surgically remove) and lymph node status. The Brigham system is divided into five stages:
- Stage I – Mesothelioma cancer is resectable and lymph nodes are not involved
- Stage II – Mesothelioma cancer is resectable, but lymph nodes are involved
- Stage III – Mesothelioma cancer is unresectable and has spread to the chest wall, diaphragm, heart, or abdominal area. Lymph nodes may or may not be involved.
- Stage IV – Distant metastatic mesothelioma cancer