Treatment by Stage for Mesothelioma

Mesothelioma is a rare form of cancer that is typically related to asbestos exposure. There are three types of mesothelioma – pleural (lung), peritoneal (abdomen) and pericardial (heart).

Pleural mesothelioma is the most common form of mesothelioma, accounting for 60 to 70 percent of all cases. Peritoneal and pericardial mesotheliomas are much less prevalent, representing only 30 to 35 percent and 5 percent, respectively.
 
Mesothelioma is often difficult to diagnose because there is a latency period of 20 to 40 or more years before the onset of symptoms. Only 2,000 to 3,000 new cases are diagnosed each year, with most patients being men between 50 and 70 years old. Complicating matters, the disease’s symptoms are usually similar to those of other common sicknesses, and patients are sometimes mistakenly treated for other ailments.

A majority of patients with mesothelioma worked closely with asbestos in mining, manufacturing or construction industries. A number of men who served in the United States Navy and worked in its shipyards have also developed the disease because asbestos was used exclusively in the construction of ships. There are also instances of family members of these workers developing the disease due to second-hand exposure in which asbestos fibers were attached to the worker’s work clothes.

Mesothelioma is a unique cancer because it does not have one solid, detectable mass. Instead, the tumor sprawls along the lining (mesothelium) of the lungs, heart and abdomen. A common symptom of mesothelioma is pleural effusion (fluid buildup) in the pleural area between the lungs and the chest wall. Oftentimes, this is detected by CT scan or chest x-ray. Mesothelioma is often confirmed following a number of procedures including a biopsy, tissue test, MRI and PET scan.

Mesothelioma is usually regarded as localized if the cancer is found only where it began. It is considered advanced if it has spread to other portions of the body.

Once diagnosed, doctors will determine how advanced it is, how much it has metastasized (spread), and if there’s any lymph node involvement. This process is called staging. Mesothelioma, however, does not follow the standard cancer staging system because the cancer is unpredictable in the way that it grows.

Currently, there are two staging systems for pleural mesothelioma – the TNM system and the Butchart system. However, there is not a standard staging system for peritoneal or pericardial mesotheliomas. The TNM system focuses on how much tumor size, lymph node analysis, and if the cancer has metastasized. The Butchart system, older but more widely used than the TNM, focuses exclusively on the mass of the primary tumor. While there are minor differences between the two, they are quite similar.

The TNM system, also referred to as the International Interest Group staging system, is an acronym for Tumor (size and if it has spread), Nodes (lymph node involvement), and Metastasis (if cancer has spread to other organs). TNM has four stages: 

Stage IA – cancer is evident on only one side of the outer layer of the pleura along the chest wall, diaphragm or pericardium.
Stage IB – cancer has spread to interior pleura layer nearest the lung affected, diaphragm or pericardium, and remains on only one side of the best.
Stage II - cancer has spread from the left or right lung pleura to lymph nodes near the affected lung on the same side. It is possible that the cancer may have spread into the lung, pericardium or diaphragm or the side in which cancer is evident.
Stage III – cancer has attached itself to the chest wall, heart, esophagus or other vital organs within the chest cavity. There may or may not be lymph node involvement near the lung on the same side.
Stage IV – cancer has metastasized to lymph nodes on other side of the chest or into the lung or pleura on the opposite side. The cancer has also spread into the abdomen or heart or other vital organs.

The Butchart system, like the TNM system, also has four stages.

Stage I – cancer is evident in the left or right pleura and could involve the lung, pericardium or diaphragm the same side as the cancer.
Stage II – cancer has attached itself to the chest wall, esophagus, heart or lymph nodes on both sides of the chest
Stage III – cancer has attached itself to the peritoneum and nearby lymph nodes. It is likely that lymph nodes outside the chest cavity are involved.
Stage IV – cancer has spread to other parts and vital organs in the body.

Another, newer system called the Brigham system has also been recently developed. Unlike the TNM and Butchart system, however, the Brigham system is based on whether or not the tumors can be surgically removed. The Brigham system also contains four stages:

Stage I – lymph nodes are not involved and cancer can be removed.
Stage II – lymph node involvement is evident but cancer can still be removed.
Stage III – cancer cannot be removed because it’s attached to the chest wall, heart, or diaphragm. Lymph node involvement is irrelevant at this juncture.
Stage IV – cancer has spread throughout the body.

Regardless of the staging system used, it is necessary that the cancer be localized (Stage I) in order to have an effective, aggressive treatment plan. Unfortunately, mesothelioma is often diagnosed when it’s already very advanced. When the cancer has progressed into Stages II to IV, it is treated the same regardless of the staging. Depending on the treatment plan, it is possible that mesothelioma may return in its original location. It is more common, however, that the cancer will turn up in another portion of the body.

'Treatment by Stage for Mesothelioma' Resources:
  1. Brayton Purcell LLP, Mesothelioma Network. "Mesothelioma Diagnosis, Staging"
  2. MesotheliomaHealth.org, "What are the Staging Systems of Mesothelioma?"
  3. Danziger & De Llano, Mesothelioma-Net.org, "Mesothelioma Cancer Stages, Staging"
  4. Mesothelioma Plus, TMN Solutions. "Mesothelioma Stages - Mesothelium Malignant Cancer Cells"
  5. Mesothelioma SOS, Mesotheliomasos.com, "Mesothelioma Stages "
  6. Cancer Research UK, CancerHelp.org.uk, "The stages of mesothelioma"
  7. The David Law Firm, MesotheliomaWeb.org, "MESOTHELIOMA DIAGNOSIS QUESTIONS"