Mesothelioma and its causes

Mesothelioma is a rare, malignant cancer of the mesothelium, the protective membrane that covers the body’s internal organs. The mesothelium is composed of two layers with fluid between that allows organs to move smoothly within the body. Three types of mesothelium exist; each can be the site of mesothelioma. The pleura line the lungs and chest wall, the peritoneum lines the abdominal cavity, and the pericardium surrounds the heart. The most common form of mesothelioma is of the pleura. Mesothelioma causes the cells of the mesothelium to divide abnormally. Cancer cells then spread to nearby organs and tissues damaging them. The cancer can also metastasize or spread throughout the body.
Exposure to asbestos is the leading cause of this type of cancer. Very few cases have been reported due to other causes. Although rare, about 2,000 to 3,000 cases are diagnosed annually. This is approximately 3 percent of the cancers diagnosed in the United States each year. More frequent in men, this cancer is one of the deadliest.
Asbestos fibers are inhaled or ingested during exposure. The fibers become trapped inside the body cavities where they come into contact with the mesothelium. The fibers then act as an irritant causing infection and inflammation. Most cases of mesothelioma do not occur until many years after exposure. Latency, or the time from exposure to development of disease, begins at 15 years, peaks between 30 and 40 years, and continues for 50 or more years.
Symptoms of pleural mesothelioma include pain of the chest wall, fluid buildup, shortness of breath, anemia, excessive tiredness, coughing, hoarseness, and blood in material coughed up. Abdominal cases generally have no symptoms until the disease is in the later stages. The symptoms include pain in the abdomen, bowel function problems, weight loss, and the presence of a mass located in the abdomen.
Treatment takes the form of traditional cancer therapies including surgery, radiation and chemotherapy. Because this cancer is very hard to treat, a combination of these techniques is often used.
Most at risk are those who experienced occupational exposure. Many industrial and construction workers were exposed on the job. Asbestos was widely used throughout most of the 20th century despite knowledge of its hazards. At more risk than other veterans, members of the Navy from WWII through the war in Vietnam were exposed to high levels of asbestos contamination aboard ships. Veterans, construction workers, miners, and firefighters are some of the occupations with the highest risk. Secondhand exposure has been documented in some cases. Family members of those exposed to asbestos at work were then exposed as the fibers were brought home in clothing and hair.