Mesothelioma Staging

Mesothelioma Staging

Mesothelioma is a rare form of cancer, accounting for only three percent of all cancers diagnosed each year. Because the symptoms of mesothelioma are rather general and similar to other less serious conditions, mesothelioma may initially be diagnosed as something else.

Medical history, a physical exam, imaging tests and blood tests may help to diagnose the cancer and determine its spread. Mesothelioma staging is a process by which, through either clinical or pathological evaluations, the extent and spread of the cancer is summarized as a stage, I-IV.

Understanding the TNM System

Currently, only pleural mesothelioma is described by the TNM staging system by the American Joint Committee on Cancer (AJCC) because the other types of mesothelioma are rare. The TNM staging system for mesothelioma focuses on three important factors for understanding the spread and development of cancer.

TNM staging stands for Tumor, the size and extent; Nodes, the spread of the cancer through the lymph nodes; and Metastasizes which describes the spread of the cancer throughout the body. Each factor is assessed and rated where 0 indicates that there is no evidence of a tumor or spread and the increasing numbers correlate with increasing severity of that particular factor.

Stage Grouping for Pleural Mesothelioma

After each factor is rated, the ratings are grouped and a stage is determined:

• Stage I Pleural Mesothelioma: The cancer is localized to either the right or left pleural lining. The cancer has not metastasized (spread) to any other sites or lymph nodes.
• Stage II Pleural Mesothelioma: The cancer affects either the right or left pleural lining and may have spread to a lung or the diaphragm. The lymph nodes are not affected.
• Stage III Pleural Mesothelioma: Other areas within the chest may now be involved. The cancer may now extend into the chest wall and may or may not have spread to the lymph nodes.
• Stage IV Pleural Mesothelioma: In the most advanced stage of mesothelioma, the cancer may have spread across the chest. It has either metastasized (spread) to distant sites or spread to the lymph nodes.

Subtypes of Mesothelioma

There are three sub-classifications of mesothelioma based on the way the cells look under a microscope:

• Epithelioid
• Sarcomatoid (fibrous)
• Mixed (biphasic)

The majority of mesotheliomas are found to be the epithelioid type. These account for 50 to 60 percent of all mesotheliomas, and tend to have a better prognosis than the other types. Sarcomatoids are the least common of the three types, accounting for only 10 to 20 percent of all cases. The mixed (biphasic) type has both epithelioid and sarcomatoid characteristics and accounts for 30 to 40 percent of all cases.

Understanding Mesothelioma Staging

The mesothelioma staging system provides a basis for assessing the prognosis (outlook) and available treatment options. Other factors, such as age, general health and the presence or absence of certain symptoms, may also play a role.

For treatment purposes, doctors may simplify the stage of the mesothelioma to either resectable (removable by surgery) or unresectable. Generally, most stage I mesotheliomas are found to be resectable, and some stage II or III cases may also be resectable depending on the subtype, spread and the patient's overall health.

At Cancer Treatment Centers of America (CTCA), we believe that every case is as unique as the person it affects. The mesothelioma staging process is the beginning of the treatment process. Understanding the disease makes it possible for you and your CTCA care team to design a mesothelioma treatment plan that is right for you.

Next Topic: Mesothelioma Treatment