Written by: Devin Golden
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Important Facts About Mesothelioma Stages
- There are four stages of mesothelioma, increasing as the cancer worsens.
- The stage of mesothelioma depends on the size of tumors, how far they’ve spread and whether they’ve reached lymph nodes.
- The stage determines which treatment options are best for a case.
- Peritoneal mesothelioma uses a unique staging system called the peritoneal cancer index.
How Doctors Determine Your Stage
Staging involves tests to learn how advanced your mesothelioma is. This is accomplished through a CT scan, PET scan or surgical methods.
These tests allow doctors to see how far the mesothelioma has spread and the size of tumors. The spread of this cancer is known as mesothelioma metastasis.
The Basics of Mesothelioma Stages
The primary factor in how doctors stage mesothelioma is metastasis. Mesothelioma forms primarily in one of two protective linings: the pleura (between the chest wall and lung cavity) or the peritoneum (covers the abdominal cavity). Stages advance as the cancer moves further from these original sites.
If you have mesothelioma, knowing the stage is vital to determining your best treatment plan. The different stages provide boundaries for physicians as they recommend treatment options.
Pleural Mesothelioma Stages
There are three staging systems for pleural mesothelioma. The outline below follows the Tumor, Node, Metastasis (TNM) Staging System.
Similar to stage 1, this stage is split into 3A and 3B. The TNM system differentiates the two by how far the cancer has spread. While still considered localized metastasis, stage 3B is more challenging for surgery.
Peritoneal Mesothelioma Stages
Peritoneal mesothelioma staging involves a different system than the one for pleural mesothelioma. Peritoneal mesothelioma rarely involves metastasis to lymph nodes, so doctors don’t rely on that characteristic for staging. They instead look at the extent of the tumors in the abdominal cavity and follow the peritoneal cancer index (PCI).
The peritoneal cancer index is the primary staging system for peritoneal mesothelioma. It applies a score based on how far the cancer has spread within the abdomen.
13 Sections of the Abominal Cavity
The PCI scores on a range of 0-39. There are 13 sections in the abdomen, and each receives a score between 0 and 3. If a section has no signs of mesothelioma, it receives a 0 score. If the section is overrun with tumors, it receives a 3.
Some doctors simplify the PCI by correlating a score to one of the four stages:
PCI OF 1-10
PCI OF 11-20
PCI OF 21-30
PCI OF 31-39
The lower the PCI score, the more treatment options are available. However, you should always receive a second opinion after your diagnosis.
Mesothelioma survivor Alexis K. was originally diagnosed with late-stage peritoneal mesothelioma. Her cancer was considered inoperable. A second opinion revealed a less-advanced stage. Alexis underwent curative surgery and as of 2021, she has survived for 13 years and counting.
The three systems used for staging pleural mesothelioma are TNM, Butchart and Brigham. The primary staging system for peritoneal mesothelioma is the PCI.
The TNM Staging System is used the most. It is a four-stage system developed by the American Joint Committee on Cancer (AJCC) and the International Union for Cancer Control (IUCC).
It evaluates three aspects of the cancer: tumor size (T), lymph node involvement (N) and metastasis (M). Each aspect receives a classification.
THE T CATEGORY
The T category considers whether mesothelioma tumors grew within the pleural space and invaded nearby tissue:
- TX means the tumors cannot be measured.
- T0 means the tumors can’t be found.
- T1, T2, T3 and T4 measure the tumors’ collective size and spread.
THE N CATEGORY
The N category focuses on lymph nodes:
- NX means lymph node involvement can’t be evaluated.
- N0 means there is no lymph node involvement.
- N1, N2 and N3 are classifications for lymph node involvement, with numbers ranging in how many are affected and how much they’ve swollen.
THE M CATEGORY
The M category focuses on metastasis to other areas of the body:
- M0 means no metastasis has occurred (the disease remains local).
- M1 means the mesothelioma has spread to distant organs or tissues.
The AJCC and IUCC update the TNM Staging protocol every six or eight years as cancer research and treatment evolves. The system was last updated in 2018 to split stage 1 into 1A and 1B.
Developed by Dr. Eric Butchart in 1976, the Butchart System is the oldest system for determining mesothelioma staging. It consists of four stages and focuses on the size of the tumors. It mostly ignores the number of tumors or the spread.
Dr. David Sugarbaker, who passed away in 2018, developed the Brigham Staging System while working at Brigham and Women’s Hospital in Boston. This system focuses on whether surgery is an option in a mesothelioma case.
The system considers location, size and spread of the cancer. Stage 1 and stage 2 patients are candidates for surgery.
What Is the Next Step After Staging?
Once staging concludes, patients should review their treatment options with their primary doctor. Depending on the stage of your mesothelioma, you may be eligible for life-saving surgery.
If you are in a stage that prevents you from receiving curative treatment, then you should consider getting a second opinion. This may provide new treatment options to extend life. Get connected to a specialist today using our free Doctor Match program.
Common Questions About the Stages of Mesothelioma
What are the stages of mesothelioma?
There are four stages of mesothelioma. As the disease progresses and spreads further in the body, the stage increases:
- Stage 1 involves tumors on one or both sides of the lungs’ lining, known as the pleura.
- Stage 2 has tumors spreading into the lung cavity and possibly reaching lymph nodes.
- Stage 3 involves tumors reaching distant lymph nodes, lung tissue and fat between the lungs.
- Stage 4 has tumors on the opposite side of the chest, the diaphragm and the peritoneum.
How are mesothelioma stages determined?
The stage of mesothelioma depends on how big the tumors are and how far they’ve spread in the body. Utilizing diagnostic imaging, doctors often focus on the size of the primary (original) tumor for staging this cancer. The stage of a diagnosis may affect the treatment options available to a patient.
How is peritoneal mesothelioma staged?
For peritoneal mesothelioma, doctors use the peritoneal cancer index (PCI) to quantify the cancer’s scope within the abdominal cavity. Doctors score each of the 13 sections between 0 and 3 based on if the cancer has spread there. They add up the scores and correlate it to one of the four stages.
What is the prognosis for each stage of mesothelioma?
The average survival rate decreases as the stage increases. For pleural mesothelioma:
- Stage 1 average survival is 20 months.
- Stage 2 average survival is 19 months.
- Stage 3 average survival is 16 months.
- Stage 4 average survival is 11 months.
What are the end stages of mesothelioma?
The end stages of mesothelioma are the latter two stages, which are stage 3 and stage 4. Most people with mesothelioma are diagnosed in stage 3.
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Last Edited: September 8, 2022.