Types of Mesotheilioma
There are three types of malignant mesotheilioma—pleural, peritoneal, and pericardial mesotheilioma. Each is named after the place of origin within the body, but while they all develop at different points, they develop in the same type of cells, called mesothelial cells. Mesothelial cells form thin membranes around the body’s organs, providing support and protection.
Why does Mesotheilioma Develop?
Asbestos is a known human carcinogen, but the way in which asbestos causes the development of cancer is not completely understood. What is known is that inhaled asbestos fibers become trapped in the lungs, where they cause persistent irritation and inflammation of delicate lung tissue. These conditions promote the types of mutations that can eventually lead to the growth of malignant cells. If those cells are mesothelial, then the result is the development of mesotheilioma.
Regardless of the point of origin, all forms of malignant mesotheilioma develop as a result of exposure to asbestos (or asbestos-like minerals). The point of origin usually reflects the way in which asbestos exposure occurred. For this reason pleural mesotheilioma is the most common form of the cancer, as most asbestos exposure is via inhalation.
Pleural Mesotheilioma
Pleural mesotheilioma accounts for around 70% of all diagnosed cases of mesotheilioma. This type of cancer develops in the pleural membranes which surround and support the lungs. As the cancer develops, the pleural membranes begin to thicken, and fluid begins to collect between membrane layers. These changes in lung tissue account for many of the initial symptoms of pleural mesotheilioma, as the result is considerable pressure and stress on the lungs and respiratory system. Symptoms include painful and difficult breathing, persistent dry cough, and chest pain, as well as more general symptoms such as fatigue, fever, unexplained weight loss, and night sweats.
Diagnosis of pleural mesotheilioma typically involves blood tests, biopsy of tissue or fluid, and medical imaging tests such as x-rays. These not only diagnose the cancer, but also determine how far it has advanced. Stage one and stage two mesotheilioma patients typically have more treatment options than patients with stage three or four cancer.
The two most commonly used treatment options for pleural mesotheilioma are surgery and chemotherapy. Surgery may involve the removal of part or all of one lung, while chemotherapy is the standard follow-up treatment which kills residual cancer cells. People with more advanced disease may not be good candidates for surgery, as it is a physically stressful process. In these cases, radiotherapy, chemotherapy, and palliative treatments can provide relief from pain and discomfort.
Peritoneal Mesotheilioma
Peritoneal mesotheilioma accounts for around 25% of all diagnosed mesotheilioma cases, and develops in the lining of the abdominal cavity. As with pleural mesotheilioma, early symptoms of peritoneal mesotheilioma are related to membrane thickening and fluid build-up, and the resulting pressure placed on many of the body’s organs. Symptoms of peritoneal mesotheilioma may include abdominal swelling, weight loss, nausea or vomiting, and diarrhea or constipation. Noticeable lumps may develop as the cancer advances.
Diagnosis of peritoneal mesotheilioma is similar to pleural diagnosis, involving tests such as biopsies, scans, and x-rays. Unlike pleural mesotheilioma, however, there is currently no recognized “staging” method for the peritoneal variety, and this lack has largely prevented the development of any systematized treatment regime.
Treating peritoneal mesotheilioma is difficult, in part because this form of cancer can spread throughout the abdominal cavity very quickly. In addition, peritoneal mesotheilioma can metastasize more readily than the pleural or pericardial types. Surgery is rarely an option, and when it is, is usually palliative.
Pericardial Mesotheilioma
Just 5% of diagnosed cases of mesotheilioma are pericardial. This form of cancer develops in the membrane which surrounds the heart, causing symptoms such as palpitations, irregular heartbeat, chest pain, and difficult breathing. One particular problem is that these symptoms closely resemble those of other cardiac conditions, and this makes pericardial mesotheilioma more difficult to diagnose. This form of cancer is often diagnosed so late that there are no effective treatment options left. Even when diagnose is made early, surgery is a risky prospect due to the proximity of the heart.
