The Staging Systems of Mesothelioma

Mesothelioma is a cancer of the mesothelium, or lining, of the chest, lungs, or abdomen. Mesothelioma that affects the pleural or chest cavity is called pleural mesothelioma and is the most common form. Peritoneal mesothelioma affects the peritoneum, which is the tissue that lines the organs in the abdomen. Since nearly all cases of malignant mesothelioma are caused by asbestos exposure, mesothelioma is sometimes called asbestos cancer.

Because mesothelioma can take up to five decades to develop after the asbestos exposure that caused it, and because the disease is relatively obscure, diagnosis often does not occur until the later stages. Compounding these difficulties is the fact that mesothelioma symptoms often mimic other diseases. Correct diagnosis and staging is both difficult and imperative.

Staging is used to describe severity of a patient's mesothelioma based on the condition of the primary tumor and how far it has spread in the body. Staging is important because it helps the doctor choose an appropriate treatment, it is used to estimate the patient's prognosis, and it helps identify clinical trials that may be appropriate for the patient.

The determination of staging can be clinical or pathological. Clinical staging relies on scanning tests and x-rays. Pathological staging refers to staging done at surgery.

For pleural mesothelioma there are three systems of classification used: the Butchart System, which is the oldest system for staging mesothelioma; the Brigham System, which focuses on the ability to surgically remove the mesothelioma, and the TNM Staging system, which is increasingly used by major cancer centers as a way of more precisely identifying the stage of cancers.

At present, there is no established staging system for peritoneal mesothelioma; if the disease is staged, the TNM system is generally used.