The terminology involved in mesothelioma diagnoses can initially seem foreign and confusing.  Of course, there is the terminology involved with the cancerous or non-cancerous status of a tumor, respectively labeled malignant or benign.  In the case of a malignancy, the physician will also need to determine the cancer’s staging. 

 

Mesothelioma stages- Tumor staging
The “stage” of a cancer is an assessment of its progress in the body, and there are four stages of increasing intensity used in this evaluative method.  The stage is assessed based on the size of a tumor, the extent of the cancer’s spreading, and whether the cancer has spread to the lymph nodes.  The term “localized” may be used to describe this type of tumor, which is limited to the surface upon which it originated.
In a stage one pleural mesothelioma, the tumor or lesion has not spread beyond its originating organ and is frequently superficial and surgically removable.  Obviously, the prognosis for a stage one tumor would be the best one possible, and treatment options would be the most flexible.
In a stage two pleural mesothelioma, the tumor has begun to infiltrate tissues other than the originating organ.  The cancer begins to extend to adjacent, attached structures.  In this case, the tumor has extended beyond the pleura and into either the diaphragmatic muscle or the pulmonary areas.
The third stage of pleural mesothelioma involves a tumor that has gone even further beyond the organ of origin and spread to the entire region surrounding that organ.  This type of tumor is less given to successful surgical removal. 
The fourth stage of pleural mesothelioma refers to a large tumor that extends well beyond its originating organ and invades blood vessels and nerves.  The advanced nature of the tumor prevents the possibility of surgical removal due to the extent of diffusion, or spreading.  In this stage of the disease, treatment options are the most limited.
These four stages for evaluating the primary tumor’s status are expressed through the combination of the letter T with a number from 1-4, with stage 1 symbolized as T1.  Beyond the T level of staging are the sublevels of lymph node and metastatic evaluation, expressed with a similar system and through the letters N and M, respectively. 

Mesothelioma stages- Nodal staging
The procedures for nodal staging reveal a similar system of progression as is applied to the analysis of tumor stages.  However, instead of numbers one through four, nodal staging is expressed in terms of x, 0, 1, 2, and 3.  NX refers to a situation in which regional lymph nodes cannot be assessed, and N0 designates no nodal involvement.  N1 refers to the first level of nodal metastases, with N2 and N3 designating reference to the two subsequent and increasingly infiltrated metastatic involvement of nodes.

Mesothelioma stages- Metastatic staging
The third level of mesothelioma assessment involves the degree of metastasis.  This is expressed through levels MX, M0, and M1, with MX designating an inability to assess the presence of distant metastasis, M0 representing no distant metastasis, and M1 signifying the presence of distant metastasis.
In describing the above system, this method of analysis is sometimes referred to as “TNM staging,” for Tumor—Node—Metastasis.  This is not the only method of staging, but it is the most commonly and widely used.  Additionally, it is the system recommended by the International Mesothelioma Interest Group, or IMIG.