Stages of Pleural Mesothelioma

When doctors talk about “staging” what they are referring to is a system of classifying tumors. Using the Roman Numerals I to IV, they categorize the tumor according to its size, its location, and whether it has metastasized (spread) to nearby lymph nodes or organs. The purpose of staging is so the doctor can determine the most appropriate kind of treatment and predict prognosis or likelihood of recovery. Currently, only pleural mesothelioma can be staged because no system of staging exists for peritoneal mesothelioma.

The doctor starts the staging analysis with the TNM system. It is used to classify the various characteristics of pleural mesothelioma tumor. TNM stands for tumor (T), node (N), and metastasis (M):

  • T– How large is the primary tumor and what is its location?
  • N– Has the tumor metastasized to the lymph nodes?
  • M-Has the tumor metastasized to other organs?

Each of these three groups is broken down into subgroups to describe the tumor with as much detail as possible:

Tumor – T

T0 (zero) – No tumor exists

T1 – The tumor has penetrated the ipsilateral pleura. This is the membrane lining of the lung and inner chest walls. Ipsilateral means it is on only one side of the body.

T1a – The pleura is divided into two types: the parietal pleura, which covers the chest wall and the visceral pleura, which is the part of the membrane that actually covers the lungs. In this subgroup, the tumor involves the ipsilateral parietal pleura, but not the visceral pleura.

T1b – Both the ipsilateral parietal pleura and the visceral pleura are involved.

T2 – Either of the ipsilateral pleural membranes is involved and the tumor has also penetrated either the diaphragm or the lung.

T3 – Either of the ipsilateral pleural membranes is involved. In addition, at least one of the following conditions also exists: invasion of the membrane that surrounds the thorax; invasion into the area of the chest between the lungs; one area of invasion into the chest wall muscles; or slight invasion into the lining around the heart.

T4 – Either of the ipsilateral pleural membranes is involved. In addition, at least one of the following conditions also exits:

  • Invasion into more than one area of the chest wall. Ribs may, or may not be involved.
  • Invasion has spread from the diaphragm into the abdominal cavity.
  • Invasion of any organs in the area of the chest that separates the lungs.
  • The pleura on the opposite side of the body is also involved.
  • Invasion into the spine.
  • The sac surrounding the heart is involved. This may result in fluid buildup, or invasion of the heart.

TX – This designation means that the doctor was unable to evaluate the tumor.

Node – N

N0 (zero) – It has not spread to the lymph nodes in the area around the tumor.

N1 – It has spread to the bronchopulmonary lymph nodes located inside the lungs on one side of the body and/or hilar lymph nodes located in the area where the lungs connect to other arteries, veins and vessels.

N2 – It has spread to the lymph nodes around the windpipe and/or the lymph nodes located in the area between the lungs on one side of the body, including the lymph nodes near the breast bone and the lymph nodes around the diaphragm.

N3 - It has spread to the lymph nodes in the area between the lungs on both sides of the body, the lymph nodes near the breast bone and/or the lymph nodes above the collar bone on one or both sides of the body

NX – this designation means the doctor was unable to evaluate the lymph nodes around the tumor.

Metastasis – M

M0 (zero) – It has not spread to other organs.

M1 – It has spread to other organs.

Once the doctor has finished the assessment using the TNM system, the information from the various subgroups is then combined to assign the stage of the cancer.

Stage I: The tumor has penetrated the parietal pleura on one side of the body. The visceral pleura may, or may not be involved. However, it has not spread to the lymph nodes or other organs.

Stage IA: The tumor has penetrated the parietal pleura on one side of the body, but the visceral pleura is not involved. It has not spread to the lymph nodes or other organs.

Stage IB: The tumor has penetrated the parietal pleura on one side of the body, and the visceral pleura is also involved. It has not spread to the lymph nodes or other organs.

Stage II: The tumor is defined as T2, but it has not spread to the lymph nodes or other organs.

Stage III: Either of the following conditions exists:

  • The tumor is defined as T1 or T2. It has spread to the lymph nodes in the manner described in N1 or N2. However, it has not spread to other organs.
  • The tumor is defined as T3. It may or may not have spread to lymph nodes, but it has not spread to other organs.

Stage IV: One of the following conditions exists:

  • The tumor is defined as T4. It may or may not have spread to the lymph nodes, but it has not spread to other organs.
  • Any T definition applies. The cancer has spread to lymph nodes in the manner described in N3, but not to other organs.
  • Any T definition applies. The cancer may or may not have spread to the lymph nodes, but it has spread to other organs.

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Mesothelioma?

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