Types of Mesotheileoma
There are three basic types of mesotheileoma – pleural mesotheileoma, peritoneal mesotheileoma and pericardial mesotheileoma. They are named for the specific type and location that where the cancer originates – the mesothelial cells that help lubricate and protect the major organs in the body.
What does the mesothelium do and how does mesotheileoma affect it?
The mesothelium is a generic name for a very thin layer of flat cells that lies between major organs and the walls around them. The pleural mesothelium, for instance, is a one-cell thick layer of tissue between the lungs and the chest wall. The pericardial mesothelium is a similar tissue that wraps the heart and lies between the heart and the chest wall. Peritoneal mesothelium is found in the abdomen around the stomach, intestines and other organs.
Mesothelial cells provide lubrication that allows the lungs and other organs to move, expand and contract as they work. The lubrication reduces friction and wear on the organ tissues and makes it easier for the lungs, heart and other organs to do what they have to do. Messothelioma causes a mutation of the mesothelial cells. The cells do not die off when they are supposed to, or they reproduce too fast. In either case, the mesothelium becomes thicker, and the increased numbers of mesothelial cells make too much lubrication. The end result is that the organs that are usually protected by the mesotheileoma are squeezed and eventually immobilized by the thickening of the protective layer and the increased fluids around the organs.
Pleural Mesotheileoma is the most common type of mesotheileoma, accounting for about 70% of all cases of mesotheileoma reported. It affects the tissues that line the chest cavity, in particular the tissues that line the lungs. While pleural mesotheileoma originates in the mesothelial cells, left untreated it can quickly spread to the chest wall, the lungs, the abdomen and the heart.
Typically, pleural mesotheileoma is not diagnosed until the latter stages because the symptoms mimic so many other illnesses. More than half of those diagnosed with mesotheileoma are dead within a year of the diagnosis. Less than ten percent are still alive five years after diagnosis.
When pleural mesotheileoma is diagnosed in the earlier stages, the treatment options include surgical options, chemotherapy and radiation therapy. The rate of survival is far higher for those who are diagnosed early because of the additional treatment options. In the later stages, most treatment is aimed at making the patient more comfortable and improving the quality of life rather than in removing the cancer.
Peritoneal Mesotheileoma is the second most common form of mesotheileoma, accounting for about 20% of all diagnosed cases of mesotheileoma. It affects the cells of the peritoneum, a thin layer of tissue that lines the abdominal walls. Peritoneal mesotheileoma, like all forms of mesotheileoma, only has one known cause—exposure to asbestos.
There are two ways that mesotheileoma may develop in the peritoneum. The first is direct origin, caused by asbestos fibers that are swallowed and ingested, then lodge in the peritoneum. Asbestos fibers may be swallowed when they get into the mouth or are transferred to the mouth, or when they are coughed up in sputum and then swallowed. The other way for peritoneal mesotheileoma to develop is through the spread of pleural mesotheileoma, which often metastasizes throughout the lymph nodes and mesothelial tissues.
Peritoneal mesotheileoma is often diagnosed in the latter stages because of its rarity and because patients are not always aware that they were exposed to asbestos. Early diagnosis can increase the treatment options available and add years to the prognosis of a patient diagnosed with peritoneal mesotheileoma.
Pericardial Mesotheileoma is the rarest form of mesotheileoma, accounting for only about 10% of all cases of mesotheileoma diagnosed each year. It originates in the pericardial mesothelium, the thin layer of sells that surrounds the heart. Doctors and scientists are unsure about the route that asbestos fibers take to the heart tissues, but they speculate that the tiny fibers are carried in the blood and become lodged in the tissues around the heart. The pericardium may also be affected by mesotheileoma when pleural mesotheileoma metastasizes.
Treatment for pericardial mesotheileoma is nearly always palliative, and consists of chemotherapy and radiation therapy designed to make the patient more comfortable. Surgery is very seldom an option in cases of pericardial mesotheileoma because of the risk of damage to the heart.
