Cancer staging describes how far a cancer has spread. Establishing the stage of a patient’s mesothelioma is important in determining the patient’s prognosis and treatment options.
Stage 1 describes a cancer that has been discovered early and has spread little or not at all from the original tumor site. Stage 4 describes a very advanced cancer that has spread to other locations and/or organs very distant from the original tumor. Cancer spreading to distant locations is called metastasis. When it happens, the cancer is said to have metastasized.
Imaging studies are the primary method for staging mesothelioma. By carefully examining X-rays, CT scans and/or MRIs, doctors can identify what other tissues, lymph nodes or organs are involved and how far the cancer has spread. In specific cases, blood tests and/or tissue samples can provide additional information useful in determining cancer stage.
In practice, pleural mesothelioma is the only mesothelioma with a defined staging system. The other types (peritoneal, pericardial, testicular) are so infrequent that they don’t have their own definitions for staging. Therefore doctors may describe these cancers in just two stages – localized and spread (or advanced).
Doctors have a choice of three staging systems for pleural mesothelioma.
Butchart System
The Butchart staging system has been used the longest. While many doctors have gravitated toward newer staging systems, some still use the Butchart definitions.
Stage 1 – Mesothelioma is in the left or right pleura (but not both), and may possibly have spread to the diaphragm on the same side of the chest.
Stage 2 – Mesothelioma has spread to any of the following: pleura on the opposite side, chest wall, lining of the heart, esophagus, lymph nodes in the chest.
Stage 3 – Mesothelioma has spread into the abdomen or abdominal lining, and possibly lymph nodes beyond the chest.
Stage 4 – Mesothelioma has spread through the bloodstream to other organs.
TNM System
This more recent staging system assesses stage based on the extent of the tumor (T), the degree to which lymph nodes are affected (N), and degree of metastasis (M). This system was devised by the International Mesothelioma Interest Group and adopted by the American Joint Committee on Cancer.
Stage 1 – Mesothelioma is in the left or right pleura (but not both). It may also have spread to the diaphragm, lining of the heart, or the lung on the same side.
Stage 2 – Mesothelioma has spread into nearby lymph nodes on the same side as the primary tumor. It may also have spread to the diaphragm, lining of the heart, or the lung on the same side.
Stage 3 – Mesothelioma has spread to any of the following on the same side of the body as the primary tumor: chest wall, ribs, muscle, esophagus, heart or other organs within the chest. Lymph nodes on the same side of the body may or may not be involved.
Stage 4 – Mesothelioma has spread to any of the following: any location in the chest on the opposite side from the primary tumor, any location in the abdomen, or any other location distant from the primary tumor.
Brigham System
This system developed more recently at Brigham and Women’s Hospital in Boston describes mesothelioma stages in terms of whether the cancer can be resected (surgically removed) and whether lymph nodes are affected.
Stage 1 – Mesothelioma tumor can be resected. Lymph nodes are not affected.
Stage 2 – Mesothelioma tumor can be resected. Cancer has spread to nearby lymph nodes.
Stage 3 – Mesothelioma is inoperable because it has spread too far into adjacent tissues and/or organs. Lymph nodes may or may not be involved.
Stage 4 – Mesothelioma has metastasized to other parts of the body distant from the original tumor.
Because the Brigham system has a unique purpose, doctors may use this system in addition to the TNM system.
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