Malignant mesothelioma occurs most often in people who worked around asbestos — typically, decades earlier. Research has identified other causes too.

Seattle Cancer Care Alliance (SCCA) offers comprehensive malignant mesothelioma treatment from a team of experts.

What is mesothelioma?

Malignant mesothelioma is a rare form of cancer in the tissue (mesothelium) that surrounds organs and makes special fluid that allows the organs to move.

About 75 percent of malignant mesotheliomas begin in the chest and another 10 to 20 percent begin in the abdomen.

It occurs most often in:
  • The lining of the chest and around the lungs (pleura)
  • The lining of the abdomen (peritoneum)
Less commonly, it occurs in:
  • The lining around the heart (pericardium)
  • The lining of the testicles (tunica vaginalis)


There are three main types of malignant mesothelioma. The most common, and most easily treated, is the epithelioid type. The other two types are called sarcomatoid and mixed/biphasic. 


The most common malignant mesothelioma symptoms are:

  • Chest pain
  • Shortness of breath
Other less frequent symptoms
  • Cough
  • Fever
  • Sweating
  • Trouble swallowing
  • Tiredness
  • Weight loss
Symptoms of malignant mesothelioma in the abdomen
  • Pain or swelling
  • Weight loss
  • Nausea
  • Vomiting

The same symptoms can also be caused by other conditions. See your doctor if you have any symptoms that concern you.


Your doctor will start by reviewing your medical history, asking about your symptoms and examining you. Next, you may need imaging tests, such as an X-ray or a computed tomography (CT) scan of your chest or abdomen.

To confirm your diagnosis, you will need a biopsy, which means removing tumor cells with a needle or by surgery and examining the cells under a microscope. A biopsy also gives your team information about the subtype of your disease, which helps them select the best treatment for you.


If your doctor finds malignant mesothelioma, you will have more tests to learn the extent of the cancer and to find out if the cancer cells have spread (metastasized) to other parts of your body. 

This process is called staging. It is important to know the stage of your disease in order to decide on the best treatment for you, such as whether to do surgery.

There are many ways to determine the stage. Many treatment centers, including SCCA, use the TNM system, which considers features of your tumor and whether cancer has spread to your lymph nodes or other parts of your body.

What causes it?

Most people with malignant mesothelioma have worked around asbestos. It may take decades after asbestos exposure for a tumor to develop and then for symptoms to appear.

Many people have thought of mesothelioma as a passing phenomenon that will disappear along with the use of asbestos. However, even though asbestos use has decreased dramatically in United States since the 1970s, many people who were exposed decades ago remain at risk. Asbestos is also still used in other countries around the world.

More recently, research has identified other causes of mesothelioma, including radiation therapy to the chest for another cancer or exposure to a mineral called erionite.

Some forms of mesothelioma may be inherited. Genetic tests can tell doctors whether your disease is related to a genetic predisposition. Testing could help provide information to other family members about their risk.

Smoking is not a cause of mesothelioma.

Men are three to five times more likely to get the disease than women are. Most are diagnosed in their 70s.