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What is Mesothelioma?

Malignant mesothelioma is a rare, fast-growing cancer. It starts in the cells that surround organs. These cells are called mesothelial cells.

Mesothelial Cells

A layer of special cells lines the inside of the chest, the abdomen, and the space around your heart. They are called mesothelial cells. They also cover the outer surface of many internal organs. They form a lining called the mesothelium.

The mesothelium helps protect your organs. It also allows them to move. For example, the lung moves when you breathe. The heart moves when it beats. And the organs in your stomach move when you digest food. The mesothelium has different names in different parts of the body. In the space around the heart, it is called the pericardium. In the chest, it is called the pleura. And, in the abdomen, it is called the peritoneum.

A cancerous tumor can form in any of these areas. When it does, it is called malignant mesothelioma. This is often shortened to just mesothelioma. There are four types:

  • Pleural Mesotheliomas - These start in the chest. They are the most common kind, representing nearly 75% of all cases. This is not the same as lung cancer.
  • Peritoneal Mesotheliomas - These begin in the abdomen or stomach area. They are less common, around one-fourth or nearly 25% of all cases. 
  • Pericardial Mesotheliomas - These start in the covering around the heart. They are very rare. 
  • Mesotheliomas of the Tunica Vaginalis - These start in the covering of the testicles. They are very rare. 

Some tumors of the mesothelium are not cancer. These include: adenomatoid tumors, benign cystic mesothelioma, and solitary fibrous tumor of the pleura. They are usually removed by surgery.

Risk Factors

There is a strong relationship between mesothelioma and asbestos. Most people who develop the disease have worked or lived around asbestos. Some types of asbestos are more harmful than others.

Other risk factors include:

  • Living with a person who works near asbestos
  • Exposure to zeolites, which are minerals that are chemically related to asbestos 
  • SV40 virus found in polio vaccines given between 1955 and 1963 (still being studied)
  • Radiation exposure
  • Age -- the risk increases as you get older
  • Genetic -- a change in the BAP1 gene

Signs and Symptoms

Common signs and symptoms of mesothelioma include:

  • Trouble breathing 
  • Pain in the rib cage
  • Pain or swelling in the stomach area
  • Lumps in the stomach area
  • Weight loss for an unknown reason

Diagnosis and Staging

Mesothelioma can be hard to diagnosis. It can look like lung cancer or other conditions that are not cancer. Your doctor may do the following to learn more:

Physical Exam – A complete check-up and health history. You will be asked about exposure to asbestos and past illnesses. The doctor will look for lumps or other signs of disease.

Chest X-Ray – An x-ray the organs and bones inside the chest. An x-ray is a type of energy beam that provides a picture of areas inside the body.

Complete Blood Count (CBC) – A blood sample will be taken. It will be checked for the number of red and white blood cells, the number of platelets, the amount of hemoglobin in the red blood cells, and the portion of the blood sample made up of red blood cells.

Biopsy – The removal of cells or tissue so they can be looked at under a microscope. There are different ways to do this. Most are done under anesthesia in an operating room. The most common are:

  • Fine-Needle (FNA) Aspiration of the Lung – A thin needle is used to remove tissue or fluid. This can be done in a doctor’s office.
  • Thoracoscopy – A cut is made between two ribs. A thin, tube-like instrument is inserted into the chest. The area can be viewed through a tiny camera and tissue can be taken.
  • Laparoscopy (also called Peritoneoscopy) – A cut is made in the abdominal wall. A thin, tube-like instrument is inserted. The area can be viewed through a tiny camera and tissue can be taken.
  • Bronchoscopy - A procedure to look inside the trachea and large airways in the lung for abnormal areas. A bronchoscope is inserted through the nose or mouth into the trachea and lungs.
  • Laparotomy – This is a more invasive surgery. It involves a cut in the abdomen wall. It is used when a larger sample is needed to make a diagnosis.
  • Thoracotomy – This is a more invasive surgery. It involves a cut in the chest between two ribs. It is used when a larger sample is needed to make a diagnosis.
  • Cytologic Exam - An exam of cells under a microscope to check for anything abnormal. Fluid is taken from around the lungs or the stomach area.

Stages of Mesothelioma

Treatment and Side Effects Management

There are different types of treatment for mesothelioma. Your doctor will suggest a treatment plan. It may include one or more of the following:

  • Surgery
  • Chemotherapy
  • Radiation therapy
  • Targeted therapy
  • Immunotherapy
  • Tumor treating fields (TTF)

Some treatments may be available through clinical trials. A clinical trial is a research study. Trials test new treatments or find better ways to use current treatment.

Your treatment options depend on:

  • the location and stage of the disease,
  • your overall health, and
  • your preferences about treatment.

As you start to understand mesothelioma and make a treatment plan, be sure to:

  • Ask questions. Keep asking your doctors until you understand the answers.
  • Write out questions for the doctor in advance. Take notes, or bring a friend or family member to take notes for you.
  • Talk with family, friends, and your health care team. Tell them about what’s most important to you.
  • Ask about clinical trials.
  • Consider getting a second opinion.
  • Seek support.

Learn More About Treatment & Side Effects