Introduction

Malignant mesothelioma is a rare type of cancer in which malignant (cancerous) cells are found in the mesothelium, a thin layer of tissue (known as a membrane) that covers most of the body's internal organs. About 2,000 to 3,000 new cases of malignant mesothelioma are diagnosed in the United States each year. The disease is rarely seen in people younger than 55, and it affects five times more men than women.

Malignant mesothelioma usually starts in the mesothelium lining the lungs, but it can also start in the lining of the abdominal organs or heart. In mesothelioma, the mesothelium's cells become abnormal and divide without control or order. They can invade and damage nearby tissues and organs.

Some people with malignant mesothelioma have no symptoms at first. If the mesothelioma starts in the lining of the lungs, the first symptoms may be similar to those of pneumonia, such as shortness of breath, difficulty breathing, persistent cough, and chest and abdominal pain. If the disease starts in the lining of the abdomen, the person may have lost weight and have abdominal pain and swelling, bowel obstruction, abnormal blood clotting, anemia, or fever. If the cancer has spread beyond the mesothelium to other parts of the body, symptoms may include pain, trouble swallowing, or swelling of the neck or face.

Most people who develop malignant mesothelioma have inhaled asbestos particles at work. Asbestos is a natural fiber that was once used to manufacture many industrial and household products. People who are exposed to even a small amount of asbestos fibers or who have been exposed for just a few weeks may be at risk of malignant mesothelioma. In general, the disease does not start until 35 to 40 years after the exposure to asbestos.