Mesothelioma is a rare cancer of the tissue that lines the body’s internal organs. About 2,000 new cases are diagnosed each year in the United States. Of these, 75 percent of cases affect the sac that protects the lungs, called the pleura. This type of mesothelioma is known as pleural mesothelioma. In about 10 to 20 percent of cases, mesothelioma may affect the tissue that surrounds abdominal organs — called the peritoneal membrane — causing what is known as peritoneal mesothelioma.
There are three main pathologic subtypes of mesothelioma:
- epithelioid, which accounts for 50 to 70 percent of cases
- sarcomatoid, which accounts for 7 to 20 percent of cases
- mixed type, which accounts for 20 to 35 percent of cases and contains both epithelioid and sarcomatoid cell types
Mesothelioma is a serious disease, which, at the current time, has a very low rate of long-term survival. However, if diagnosed early, treatments are available that will significantly extend life. New therapies and approaches continue to be tested and developed through our program of clinical trials.
Risk Factors
Exposure to asbestos is the main known risk factor for mesothelioma. People in occupations such as mining, milling, construction, plumbing, heating, insulation, carpentry, and electrical and shipyard work generally have had greater exposure to asbestos than those in other occupations and are therefore at higher risk of mesothelioma. Family members of these workers are also at higher risk than others because of indirect exposure to asbestos (in the clothes and hair of family members).
Following asbestos exposure, the time to development of mesothelioma may be two to four decades. Due to occupational exposure, mesothelioma is about three times more common in men than in women. Because the number of cases rises with age, there are about ten times more cases in men over age 64 than in men in their 30s.
A federally mandated ban on the production and use of all asbestos products was implemented in the US in 1989. Before its dangers were known, asbestos was a common form of building insulation and was used to make a variety of products, including roofing materials and floor tiles. Because mesothelioma takes at least 20 years to develop, the widespread use of asbestos between the 1930s and the 1960s has led to the rise in mesothelioma cases since 1970.
Smoking raises the risk of lung cancer in those exposed to asbestos, but not the risk of mesothelioma.
Symptoms
The main symptom of pleural mesothelioma is shortness of breath caused by pleural effusion — the buildup of fluid in the pleura, or membrane, surrounding the lung. The second most common symptom is chest pain due to the tumor invading the chest wall. Other symptoms may include weight loss, fatigue, and night sweats.
The primary symptom of patients with peritoneal mesothelioma, which originates in the abdomen, is abdominal swelling due to fluid buildup in the abdomen (a condition called ascites), abdominal pain, and bowel obstruction.
It is important to note that many of these symptoms may be caused by other conditions. But if you have experienced any of these symptoms and have had asbestos exposure, you should see your doctor.
