Health A-Z

Medical Content Created by the Faculty of the Harvard Medical School


What Is It?

Mesothelioma is a rare form of cancer that affects the thin membranes that line most of the body's organs. In the lungs and chest cavity, this membrane is called the pleura. In the abdomen, it is called peritoneum. The membrane around the heart is called the pericardium. Mesothelioma most often affects the lungs.

Most cases of mesothelioma are caused by exposure to asbestos. Asbestos is a naturally occurring mineral. It was once used in a variety of industrial products including

  • Insulation

  • Cement

  • Roof shingles

  • Flooring

  • Brake linings

People who made these products or worked in certain industries, such as ship building, have an increased risk of mesothelioma because they may have inhaled or swallowed dust containing asbestos particles. If they went home with dust on their clothing, family members may have been exposed to asbestos, too.

Some cases of mesothelioma have been linked to other causes. These include exposure to a radiation contrast dye used before 1960 to help blood vessels show up on x-rays. In a few cases, the cause is unknown.

People exposed to asbestos for a long time, or exposed to high levels of it, have an increased risk of mesothelioma. But even people exposed to asbestos for a short time can develop the disease. Smoking and being exposed to asbestos seems to raise a person's risk even more.

Typically, the disease develops 20 to 40 years after asbestos exposure. People usually are diagnosed with mesothelioma between ages 50 and 70. More men than women get this cancer. That's probably because men are more likely to have worked in industries that used asbestos.

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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