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What is Mesothelioma?

Mesothelial Cells

A layer of specialized cells called mesothelial cells lines the inside of the chest, the abdomen, and the space around your heart. These cells also cover the outer surface of many internal organs. The lining formed by these cells is called mesothelium.

The mesothelium helps protect your organs by making a special lubricating fluid that allows organs to move. 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, the pleura. And, in the abdomen, it is called the pleura.

A cancerous tumor of the mesothelium is called a malignant mesothelioma. This is normally shortened to just mesothelioma. Mesotheliomas generally start in four sections of the body:

  • Pleural Mesotheliomas - These start in the chest and comprise nearly 75% of mesothelioma cases. 
  • Peritoneal Mesotheliomas - These begin in the abdomen and comprise nearly 25% of mesothelioma cases. 
  • Pericardial Mesotheliomas - These start in the covering around the heart and are very rare. 
  • Mesotheliomas of the Tunica Vaginalis - These start in the covering of the layer of the testicles and are very rare. 

It is important not to confuse benign mesothelioma tumors (Adenomatoid tumors, Benign Cystic Mesothelioma and Solitary Fibrous Tumor of the Pleura) as these are generally removed by surgery and no further treatment is necessary.

It is also important not to confuse mesothelioma with lung cancer.

Risk Factors

Research is increasing regarding what we know about mesothelioma. Scientists are learning more about its causes.

Most people with malignant mesothelioma have worked or lived in places where they inhaled or swallowed asbestos. 

Other risk factors for malignant mesothelioma include the following:

  • Living with a person who works near asbestos. 
  • Exposure to zeolites, which are minerals that are chemically related to asbestos. 
  • Infection with Simian Virus 40 (SV40.) Some injectable polio vaccines given between 1955 and 1963 were contaminated with SV40. As many as 30 million people in the United States may have been exposed to the virus.

Signs and Symptoms

These and other symptoms may be signs of mesothelioma. Consult a doctor if any of the following should occur:

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

Diagnosis and Staging

Sometimes, it is difficult to tell the difference between mesothelioma and lung cancer. If a patient has symptoms that could be mesothelioma, the doctor will test for fever and high blood pressure and check general signs of health.

The patient will likely have one or more of the following tests: 

Physical Exam - An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits, exposure to asbestos, past illnesses and treatments will also be taken.

Chest X-Ray - An x-ray the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.

Complete Blood Count (CBC) - A procedure in which a sample of blood is drawn and 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.

Sedimentation Rate - A procedure in which a sample of blood is drawn and checked for the rate at which the red blood cells settle to the bottom of the test tube.

Biopsy - The removal of cells or tissue from the pleura or peritoneum so they can be viewed under a microscope. There are different biopsy procedures. Following are the most common:

Fine-Needle (FNA) Aspiration of the Lung - The removal or tissue or fluid using a thin needle. An imaging procedure is used to locate the abnormal tissue or fluid in the lung.

Thoracoscopy - An incision is made between two ribs and the thoracoscope (a thin, tube-like instrument) is inserted into the chest.

Peritoneoscopy - An incision is made in the abdominal wall and a peritoneoscope (a thin, tube-like instrument) is inserted into the abdomen.

Laparotomy - An incision is made in the wall of the abdomen to check the inside of the abdomen for signs of disease.

Thoracotomy - An incision is made between two ribs to check inside the chest for signs of disease.

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.

Cytologic Exam - An exam of cells under a microscope to check for anything abnormal. For mesothelioma, fluid is taken from around the lungs or from the abdomen.

Stages of Mesothelioma

Treatment and Side Effects Management

Different types of treatment are available for patients with mesothelioma. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. (A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer.)

Your treatment options depend on the stage of cancer, your overall health and your preferences about treatment. In metastatic disease, the location and extent of the mesothelioma is also an important consideration. If your cancer spreads to the bone, visit our bone metastases page.

You do not have to rush to make a decision, so consider the options carefully. Ask questions if you do not understand any aspect of treatment or the terms your doctors are using. Research shows that cancer survivors of all educational levels and backgrounds can have a hard time communicating with their health care team. One of the best ways to improve communication with your health care team is to prepare your visits so that you can best make use of the time.

A treatment plan is a way to deal with both the short and long term goals of managing your mesothelioma. There are several treatment options for mesothelioma, depending on the cancer stage and the patient’s age and general health. Patients have time for second opinions and to talk through all of their options with their doctors and develop a treatment plan that best fits their needs.

Learn More About Treatment & Side Effects