TNM Staging System

Malignant mesothelioma is caused when deadly asbestos fibers become inhaled or ingested. At this point, the sharp asbestos fibers become embedded in the victim’s mesothelium. This is a protective membrane or tissue layer that is present in most organs of the human body. While it is there to serve as protection, it has no defense to asbestos fibers. They enter the mesothelium, and the body has no way to remove them.

These fibers will not break down over time because asbestos is resistant to nearly everything, including the acids in the human body. The fact that it is resistant to heat, fire, electricity and caustic chemicals is the reason asbestos was used so frequently in the first place.

Once these fibers are trapped in the human body, they can metastasize into the deadly form of cancer known as mesothelioma. This process typically takes between 20 and 50 years. During that time, the cancer will grow, and tumors will form. The cancer will advance and can be classified based upon an established staging system, called the TNM Staging System.

However, as our Boston mesothelioma attorneys have seen in various cases, mesothelioma can occur in various parts of the victim’s body and then quickly spread to other parts of the body. While asbestos most commonly forms in the victim’s lungs, it is important to understand that mesothelioma is not the same as lung cancer. The type of lung cancer commonly associated with smoking, though it can occur in nonsmokers as well, is an entirely different medical condition.

Where Can Mesothelioma Form?

Mesothelioma most commonly forms in the lungs, and, when this occurs, it is called malignant pleural mesothelioma (MPM). However, it can also metastasize in the victim’s chest cavity around the lining of the heart. When this occurs, it is known as malignant pericardial mesothelioma. It can also form in the victim’s abdominal cavity, where it is called malignant peritoneal mesothelioma.

Again, it is crucial to understand that even if the tumor forms in only one of these areas, it can quickly spread to other parts of the body where new tumors will form. This is one of various reasons why malignant mesothelioma is so difficult to treat.

What is the TNM Staging System?

Once a doctor diagnoses a patient with malignant mesothelioma, one of the very next questions as is how advanced is the cancer. Diagnosis of mesothelioma doesn’t happen until the disease is in its later stages because it is asymptomatic until them. That means patients do not have long to live.

However, both length and quality of life may be extended the earlier doctors can catch it.

By properly staging the disease, medical professionals can determine the best course of action to maximize outcomes.

Doctors stage the cancer using a formal system called TNM Staging that in many cases give the patient a better idea of his or her prognosis and options. However, as noted by the American Cancer Society (, of the three types of malignant mesothelioma, malignant pleural mesothelioma is the only one for which a formal staging system such as TNM is applicable.

The letters “TNM” stand for Tumor, Nodes, and Metastasized. It is a system used by the American Joint Committee on Cancer (AJCC) and aims to provide a uniform method for staging MPM and MPM tumors.

The “T” in TNM, which stands for tumor is used to classify the extent and spread of any malignant mesothelioma tumors. The “N” describes whether mesothelioma that formed in the lungs has spread to lymph nodes in that same part of the boy. The “M” in the acronym is used to determine if the tumors have metastasized to other parts of the body. It is common for malignant mesothelioma to form first in the victim’s lungs and spread to other areas of the body through the lymphatic system.

What is the T Group?

The tumor can be classified using the TNM system to determine how advanced it is. It will be given a rating ranging from TX on the low end to T4, which is the most advanced. The specific phases are all followed:

  1. TX
  2. T0
  3. T1
  4. T2
  5. T3
  6. T4

At the first stage, TX, the tumor is present, but the main tumor cannot be assessed for one reason or another. The next stage in tumor growth, T0, involves cases where there is no evidence that a main tumor is present. This means that cancer is found in other parts of the body instead. At state T1, the cancer is present in the pleural linings of the victim’s diaphragm. This is the muscle that effectively operates the patient’s lugs and their contraction and expansion during breath. It can quickly spread to what is known as the pleural covering.

In a T2 case, the cancer is in the pleural lining in side of the lungs, as well as possible other organs. In a T3 case, the cancer has spread to the lining of one lung and either the first layer of the chest wall, the fatty mediastinum tissue, the surface of the pericardium that surrounds the heart, or the deeper layers of the patient’s chest wall.

When mesothelioma reaches the T4 stage, it has grown to the point where it cannot even be removed entirely by surgical methods. In these cases, the main tumor has likely spread to other areas of the body, such as the ribs, intercostal spaces, esophagus, trachea, or spine. It is important to note that, while other tumors can form, here we are talking about the main tumor that has spread so much that it is embedded in multiple organs other than just the lungs.

What is an N Group?

The N stands for nodes, and relates to when a tumor has spread to nearby lymph nodes. Just as in the case of the T group, a rating of NX means that the main tumor can’t be assessed in the lymph nodes for one reason or another, and N0 means that there is no evidence the tumor has spread to nearby lymph nodes. The difference being in the first group that it may have spread, but it is not detectable.

Again, as was the case with staging mesothelioma using the TNM system in the T group, the N group is classified with stages one through four with four being the most advanced.

Finally, with the M group, doctors can determine if the cancer has metastasized to different parts of the victim’s body.

If you have been diagnosed with mesothelioma, you are likely reeling. You may have numerous legal options. Our dedicated, compassionate mesothelioma attorneys can help outline those for you.

Contact Jeffrey Glassman Injury Lawyers today for a free and confidential consultation.


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