Mesothelioma Staging

When an individual is diagnosed with mesothelioma, doctors try to see how it has spread in the body and the extent of spreading. The process of determining how and the extent malignant mesothelioma has spread is called staging. It helps describe the way the cancer has spread, the areas it has spread to, and the degree or level of spreading. Staging helps determine the severity of the cancer so that doctors can define the best treatment approaches to apply.1

mesothelioma staging

 

The stage of the cancer may provide information relevant in determining the survival chances and rates of individuals because doctors know how the prognosis is likely to be. Usually, the cancer is staged in a scale of 1 to 4 using roman numbers for example, I, II, III, and IV. A lower number or scale indicates that the cancer has less spread to other parts and a higher number shows that the cancer cells have spread widely in body. Within the numbers, there are also letters used to further show the extent of spreading. A person’s cancer experience isn’t the same, but people with similar stages will most probably have a similar outlook, so the treatment may be almost the same.1

Statistics showing the outlook for some cancer type and stage are provided as survival rates. The survival rate brings some light on what portion of persons having the same cancer type and stage still survive after a given time following their diagnosis, but these rates don’t usually tell how long a person will live, but they generalize the population. They only show how likely the treatment will be successful and for how long are the individuals in the same cancer stage and type likely to survive, but not specific for every individual – just a generalized number.2

How to Determine Mesothelioma Stages?

Pleural mesothelioma is the common type of the cancer4, and it’s the only form of mesothelioma which has a formal staging system in existence. Malignant pleural mesothelioma starts within the lining of lungs and within the inner lining of chest wall4. The TNM system developed by the American Joint Committee on Cancer (AJCC) is the most used staging system for pleural mesothelioma. This staging system is usually based upon 3 important pieces of information that include the following:

  • The size or extent of tumor denoted as T – this tells whether or not the cancer has grown to reach the nearby organs or structures. It also tells whether it’s possible to have the tumor removed using surgery.
  • Spreading of the cancer to nearby lymph nodes denoted as N – it tells whether the cancer cells have spread to reach the lymph nodes.
  • Spreading to distant sites, also known as metastasis and it’s denoted as M – it tells whether the cancer has spread to reach distant organs like the pleura, lung, liver, bones or the peritoneum.

You may have a number provided after T, N, and M when staging mesothelioma, and these numbers or letters usually provide more details regarding the factor that is in question. When the letters or numbers following T, N, and M are higher, it indicates that cancer is more advanced.

When the T, N, and M categories within a person have been identified, the information is then combined in what is known as stage grouping so that the overall stage of the cancer is identified or determined. Here we have the most recent staging system for malignant pleural mesothelioma that became effective January 2018. It is a system developed by AJCC and applies only to pleural mesotheliomas meaning that mesothelioma cancers starting in other areas of the body have not yet received a formal staging system because they are less common.

Pleural mesothelioma gets a clinical stage depending on the information obtained from the physical examination, tissue biopsy, and imaging tests conducted during the diagnosis of mesothelioma1,3. When surgery is performed, there is another stage which is called pathologic stage or surgical stage usually determined by a doctor examining the tissue taken out during the operation. It’s important to understand that cancer staging is a complex thing, so if you want to know more about it, ask the doctor to try to explain to you so that you have an idea or at least you understand what it means.1

Malignant Pleural Mesothelioma Stages

AJCC stage IA, stage grouping T1, N0, M0

With IA- T1, N0, M0 the mesothelioma is within the pleura lining that lines the chest wall and within one side of a person’s chest. The cancer may or may not be affecting the pleura tissue that lines the diaphragm – this is the thin breathing muscle found below the lungs. It also may or may not be affecting the space found between the lungs known as mediastinum. The cancer also has or has not affected the pleura tissue that covers the lung. Those details indicate T1 description of the IA stage.

In addition to those details, the cancer hasn’t reached the nearby lymph nodes something indicated by N0. The cancer has not moved to distance sites denoted by M0.

AJCC stage IA, stage grouping T2, N0, M0

With IA- T2, N0, M0 the cancer is present within the pleura that lines the chest wall but on one side of the person’s chest. It is also in the pleura tissue that coats the diaphragm and the tissue that covers the mediastinum space or the tissue that covers the lung itself. The cancer is also present in the lung and it has grown to affect the diaphragm -T2

That said, the cancer has not reached nearby lymph nodes indicated by N0 and it has also not reached distant sites indicated by M0.

AJCC stage IB, stage grouping T3, N0, M0

With IB – T3, N0, MO the cancer has grown to reach the nearby structures however, it can be removed or resected using surgery. This is denoted as T3. The cancer is also present within the pleural tissue that lines the chest wall within one side of chest. It’s also present in pleura that coats the lungs, covers the mediastinum, and coats the diaphragm, within the same side of the chest. The cancer has also grown to affect at least one of these parts:

  • Endothoracic fascia- first layer within the chest wall
  • Mediastinum’s fatty tissue
  • A single spot within the deeper layers within the chest wall
  • Outer covering layer within the heart also known as the surface of the pericardium

That said, the cancer has not yet spread to reach the nearby lymph nodes N0 and it hasn’t reached distant sites M0.

AJCC stage II, stage grouping T1 or T2, N1, M0

With this stage the mesothelioma cancer is already in the chest wall lining called the pleura on one side of the person’s chest – T1. The cancer might also have grown to affect the diaphragm or it has affected the lung- T2. It has spread to attack the nearby lymph nodes within the same side of the body where the main tumor is found – N1. That said, the cancer has not reached distant sites – M0.

AJCC stage IIIA, stage grouping T3, N1, M0

In this stage the cancer has attacked the nearby structure; however, it can be removed using surgery- T3. In addition, the tumor has affected the pleura that lines the chest wall but on just one side. It has also affected the pleura tissue that coats the lungs, the mediastinum, and the diaphragm on same side. The cancer has grown to attack at least one of these areas:

  • Mediastinum’s fatty tissue
  • Endothoracic fascia – first layer within the chest wall
  • A single area within the deeper layers forming the chest wall
  • The outer covering of the person’s heart also known as the pericardium surface

That said, the cancer has affected nearby lymph nodes just within the same side of the person’s body where the main tumor is found – N1. The cancer hasn’t reached distant sites – M0.

AJCC stage IIIA, stage grouping T1-T3, N2, M0

Here the cancer may or may not have reached nearby structures, however, doctors can remove it using surgery – T1-T3. Also the cancer has spread to reach the lymph nodes within same side of the body where the tumor has developed. It also has spread to attack the lymph nodes found above the collarbone popularly known as supraclavicular lymph nodes but on either sides – N2. That said, the cancer hasn’t yet reached distant sites – M0.

AJCC stage IIIB, stage grouping T4, Any N, M0

In this stage the cancer has already grown to the extent that it cannot completely be removed using surgery procedure. Also, the tumor is present within the pleura tissue that lines the individual’s chest wall just one side of their chest. It’s also present on the pleura that coats the diaphragm, lung, and mediastinum but on the same side. Further the tumor has extended to attack one of these areas:

  • More than one area within the deeper chest wall layers including ribs or muscles
  • The diaphragm and peritoneum
  • Any of the organs within the mediastinum – trachea, esophagus, blood vessels, or thymus
  • The spine
  • It has reached across the pleura within the other side of the person’s chest
  • Has attacked the lining of the heart (pericardium) or it has attacked the heart itself.

That said, the cancer might or may not have attacked the lymph nodes – Any N, and it hasn’t spread to reach distant sites M0.

AJCC stage IV, stage grouping Any T, Any N, M1

In this stage the cancer may or may not be affecting nearby structures – Any T. Again, it may or may not be attacking nearby lymph nodes – Any N. However, it has spread to attack distant organs including the liver, bones, lung, or pleura and on other side of the individual’s body. It has also spread to the lining of the abdomen or peritoneum – M1.

There are other additional categories that may be included when staging mesothelioma but they haven’t been listed above and they include:

  • TX – this indicates that the main tumor isn’t assessed because of lack of information
  • NX- this indicates that nearby lymph nodes aren’t assessed because there lacks any information
  • T0 – this indicates that there is no evidence to show the primary tumor.

Reference List

  1. Malignant Mesothelioma Stages. https://www.cancer.org/cancer/malignant-mesothelioma/detection-diagnosis-staging/staging.html
  2. Survival Statistics for Mesothelioma. https://www.cancer.org/cancer/malignant-mesothelioma/detection-diagnosis-staging/survival-statistics.html
  3. How Is Malignant Mesothelioma Diagnosed? https://www.cancer.org/cancer/malignant-mesothelioma/detection-diagnosis-staging/how-diagnosed.html
  4. https://www.mesothelioma.com/mesothelioma/types/
  5. What Are the Most Common Mesothelioma Symptoms? https://www.asbestos.com/mesothelioma/symptoms.php

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