Mesothelioma: Staging Systems

Butchart System
This is the oldest and most used staging system for mesothelioma based on the mass of the primary tumor. It classifies the disease into four stages. Stage-I indicates presence of mesothelioma in the right or left pleura as also on the same side diaphragm. In Stage-II the chest wall is invaded by the cancer including esophagus, heart, pleura of both sides and lymph nodes. Stage-III mesothelioma is when the cancer has spread into the peritoneum or the lining of the abdominal cavity by penetrating the diaphragm. The lymph nodes lying beyond the chest may also be affected at this stage. At Stage-IV mesothelioma has spread to distant organs (metastasis) carried by the blood.

TNM System
It is a recent system based on the mass and spread of the tumor, involvement of lymph nodes and metastasis. This system determines staging by the three variables, viz. tumor (T), Lymph nodes (N) and metastasis (M). Stage-I of this system indicates mesothelioma has invaded the right or left pleura with possible invasion of the lung, pericardium or diaphragm of the same side. Involvement of lymph nodes at this stage is not indicated. At Stage-II the cancer has spread to lymph nodes in the vicinity of the pleura and then to the lung, pericardium and diaphragm on the same side. At Stage-III, mesothelioma invades the chest wall including muscles, ribs, esophagus, heart and other same side organs in the chest with or without invading lymph nodes on the same side as the tumor. Mesothelioma spreads to chest lymph nodes at Stage-IV opposite the side of the primary tumor and extends to opposite side organs including abdominal cavity and distant organs (metastasis).

Brigham System
Stage-I and II of this system indicate mesothelioma is resectable without and with involvement of lymph nodes respectively. At Stage-III unresectable mesothelioma extends to chest wall including heart through peritoneum or diaphragm with or without involvement of lymph nodes. Metastasis sets in at Stage-IV of this system.