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Mesothelioma Metastasis

As cancers progress, they can spread to other parts of the body. This process is called metastasis. Metastasis happens when cancerous cells dislodge from a tumor and travel through the body's lymphatic or vascular system to other locations in the body. Eventually, these loose cells stick to an organ or body tissue and start growing new tumors there.

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What Affects Mesothelioma Metastasis?

When mesothelioma cells form new tumors through metastasis, it is considered to be mesothelioma and not a new form of cancer.

For example, if pleural mesothelioma cells break away and grow a new tumor on a patient’s kidney, the new growth is still called mesothelioma, not kidney cancer, because the disease is caused by mesothelioma cells.

One of the factors for mesothelioma metastasis is the original location of the tumor. For example, pleural (lungs) and peritoneal (abdomen) mesothelioma tend to be locally aggressive cancers, which means they usually metastasize in organs or muscles that are close to the lungs or stomach.

Mesothelioma Cell Type

The cellular structure of the mesothelioma also has an influence on where the mesothelioma can spread and how quickly the growth can occur.

There are two different types of mesothelioma cells: epithelioid and sarcomatoid. How far and how fast cancer spreads depends on which type of cancer cells a person has, or, in the case of mixed or biphasic cell mesothelioma, which kind of mesothelioma cell is more dominant.

Epithelioid Mesothelioma Metastasis

Epithelioid cells are cube-like and uniform in appearance. When they do break off from the original tumor and travel throughout the body, they travel through the lymphatic system.

The cells’ boxy-shape causes this type of mesothelioma to spread slowly. Because of these characteristics, they tend to stay closer to the original cancer site.

The lymphatic system is a part of the immune system, and it carries liquid and white blood cells throughout the body. However, the lymphatic system is filled with a series of nodes or filters that trap waste products and debris, such as a cluster of cancer cells.

Sarcomatoid Mesothelioma Metastasis

Sarcomatoid cells are large cylindrical cells that taper at two ends. The round shape makes it easier for these cells to travel through the body’s bloodstream or vascular system.

The vascular system does not contain gateways, like the lymph nodes, so the sarcomatoid cells can travel further away from their point of origin than they would be able to if they were moving in the lymphatic system.

Biphasic Mesothelioma Metastasis

In mixed-type or biphasic mesothelioma, the tumors are made up of a combination of both epithelioid cells and sarcomatoid cells. However, it’s not a 50/50 split between the two types.

The tumors will be made up of more of one kind of cell, and they will metastasize accordingly. Meaning, if the tumors are made up of more epithelioid cells, then cancer will spread more slowly and stay more local.

But, if there are more sarcomatoid cells than epithelioid cells, then the disease will spread faster and farther.

Mesothelioma Metastasis Sites

The speed at which metastasis occurs, and how far away the new tumors can form, depends mainly on the cell structure of the patient’s mesothelioma.

Doctors can anticipate where the mesothelioma might spread to, based on where it originated. Understanding potential patterns for spread allows doctors to know what other areas to monitor for new tumors.

It’s important to note that the below lists are not exhaustive. While these sites are some of the most common locations for the growth of new mesothelioma tumors, the disease can spread to other places throughout the body.

A study found pleural mesothelioma cells in a patient’s thigh muscles, despite pleural mesothelioma being a locally aggressive cancer, that is, a form of cancer that tends to only spread to nearby tissues and organs.

Pleural Mesothelioma Metastasis Sites

Pleural mesothelioma starts in the lining of the lung, known as the pleura. It is the most common form of mesothelioma and is caused by inhaling asbestos fibers.

Pleural mesothelioma can spread to:

  • Mediastinum (the space between the lungs)
  • Muscles and ribs of the chest lining
  • Esophagus
  • Thymus
  • Trachea
  • Opposite lung
  • Diaphragm
  • Chest lymph nodes
  • Liver
  • Kidneys and adrenal glands
  • Bones

Peritoneal Mesothelioma Metastasis Sites

Peritoneal mesothelioma rarely leaves the abdomen. This is unlike pleural mesothelioma, which can travel throughout the body to a person’s liver or kidneys.

Peritoneal mesothelioma can spread to:

  • Other abdominal organs
  • Liver
  • Spleen
  • Tissue covering the small intestine and colon
  • Space between the lungs and the walls of the chest

Pericardial Mesothelioma Metastasis Sites

Pericardial mesothelioma is rare, and there is not much research or information out there about where the cancer might spread.

However, one area that pericardial mesothelioma is known to metastasize in is the lungs.

Mesothelioma Staging

There are four stages of mesothelioma. Each of these stages corresponds with how much the cancer has metastasized.

Stage one has the least amount of metastasis, and stage four has the highest amount. What stage of the disease a patient affects the type of treatment a patient can receive.

Currently, there is not a standard staging system for mesothelioma.

However, the most common staging system for pleural mesothelioma is the American Joint Committee on Cancer (AJCC) TNM system, which looks at the size of the original tumor (T), whether it has spread to any nearby lymph nodes (N), and if it has metastasized (M) to distant sites.

The other two staging systems are Brigham and Butchart.

Stages 1 and 2

In stages 1 and 2 of pleural mesothelioma, the cancer has only spread locally. Meaning, while the patient might have the disease in their diaphragm or local lymph nodes, it is still unilateral — that is it has remained on one side of the body.

In stages 1 and 2, most treatment methods like surgery are still viable options.

Stage 3

In stage 3 the disease has spread further. The disease may have spread to the esophagus, on to the surface of the pericardium, to the lymph nodes above the collarbone or on to the other side of the body. In stage 3 it has not spread to a distant organ such as the liver or the other lung.

At this point, surgery might still be an option to remove the mesothelioma. However, patients will likely also receive chemotherapy or radiation therapy to improve their survival rate.

Stage 4

By stage 4 pleural mesothelioma, the cancer has spread further in the body to locations such as bones, the other lung or the lining of the abdomen.

At this point, all treatments are palliative and designed to make the patient as comfortable as possible and to increase their life expectancy.

Treatment for Advanced Stage Mesothelioma

While the current treatments are less effective the more the cancer has progressed, many clinical trials are looking into improving the standard of care treatments or finding new ones.

Right now, there is a significant focus on the benefits of immunotherapy and how doctors can teach the body’s lymphatic system to recognize and destroy mesothelioma cells.

Because each mesothelioma case is unique, it’s essential to get a second opinion from a mesothelioma specialist, when being diagnosed and looking at treatment options.

If you or a loved one has been diagnosed with mesothelioma, contact our Justice Support Team.

Call us at (888) 360-4215 or request our FREE Mesothelioma Justice Guide for information about how we may be able to help you receive the financial compensation you deserve.

Mesothelioma Support Team
Reviewed by:Dr. Assuntina Sacco

Board-Certified Oncologist

  • Fact-Checked
  • Editor

Assuntina Sacco, MD is an Associate Professor of Internal Medicine at the University of California, San Diego (UCSD) Moores Cancer Center, where she also serves as the Medical Director of Infusion Services. She is a board-certified medical oncologist trained to treat all solid tumor types, with the use of chemotherapy, immunotherapy, targeted therapy, and clinical trials.

Dr. Assuntina Sacco is an independently paid medical reviewer.

Stephanie KiddWritten by:

Editor-in-Chief

Stephanie Kidd grew up in a family of civil servants, blue-collar workers, and medical caregivers. Upon graduating Summa Cum Laude from Stetson University, she began her career specializing in worker safety regulations and communications. Now, a proud member of the American Medical Writers Association (AMWA) and Editor-in-Chief of the Mesothelioma Justice Network, Stephanie serves as a voice for mesothelioma victims and their families.

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