Mesothelioma is a rare form of cancer that affects cells that can be found in the mesothelium, a protective membrane surrounding the majority of the body's internal organs. The cells that make up this membrane protect the organs by making a special fluid that allows them to move, including helping the lungs to move during breathing.
The vast majority of people who develop the deadly disease have inhaled asbestos particles, often through their jobs, according to the National Cancer Institute. In fact, a history of asbestos exposure in the workplace is reported in approximately 70 to 80 percent of all cases.
Asbestos was originally prized by the ancient Greeks and Romans due to its resistance to fire and use as an insulator. Use of the mineral increased rapidly during the 19th century, particularly during the Industrial Revolution. By the mid-1960s, however, it was known that exposure to asbestos could cause a range of serious illnesses.
In addition to mesothelioma, the inhalation of the deadly mineral fibers can cause lung cancer and asbestosis. The World Health Organization estimates that asbestos-related diseases kill approximately 107,000 people around the world each year.
According to the American Cancer Society (ACS), there are four types of mesothelioma, and these types are based on how the cells look under the microscope.
Epithelioid is the most common type of mesothelioma, and those with this type typically have a better long-term prognosis than those with the other kinds. Sarcomatoid or fibrous refers to approximately one to two per every 10 cases of mesothelioma, according to the American Cancer Society.
Mixed (biphasic) mesothelioma includes specific features of the first two types, but this kind occurs in approximately three to four out of every 10 mesothelioma cases. Finally, Desmoplastic mesothelioma is the fourth type and is extremely rare, according to the ACS.
Approximately 75 percent of mesothelioma cases begin in the chest cavity, and these instances are referred to as pleural mesotheliomas. Approximately 10 to 20 percent of the diseases begin in the abdomen, while those that begin around the heart are extremely rare, the ACS says.
While the reported incidence rates of mesothelioma have grown over the past 20 years, it is still a relatively rare cancer. In the U.S., approximately 2,500 new cases of mesothelioma are diagnosed each year. The cancer typically occurs more often in men than in women and the risk of developing it increases with age. However, the cancer can appear in both men and women of any age, according to the National Cancer Institute.
The symptoms of mesothelioma may not appear until 30 to 50 years after initial asbestos exposure. According to the National Cancer Institute, these symptoms generally consist of shortness of breath and chest pain due to the accumulation of fluid in the pleura. Other symptoms of the various types of the disease can include weight loss, swelling, abnormal blood clotting, anemia and fever.
Due to the fact that many of these symptoms are common for a number of conditions and the fact that the symptoms may not show for decades after asbestos exposure, it can be extremely difficult for doctors to diagnose mesothelioma.
Treatment of mesothelioma depends on the cancer's location, the general health of the patient and the stage of the disease. Some of the more standard treatment options include radiation therapy, surgery and chemotherapy. In some instances, these treatments are combined, according to the National Cancer Institute.
While these treatments are available for some people with mesothelioma, a cure is not possible for many people who suffer from the disease, according to the Mayo Clinic.