Types of Mesothelioma
According to the part of the body affected by mesothelioma, we can generally classify mesothelioma into the following types:
1. Pleural Mesothelioma
2. Peritonial Mesothelioma
3. Pericardial Mesothelioma
Pleural Mesothelioma - affects the chest and lung
This is the most common type of mesothelioma. About 75 percent of all mesothelioma cases are pleural. This is where the cancer affects the lungs and the protective lining and cavity of the lungs. This particular form of mesothelioma can spread to numerous organs in the body - even the brain - and tends to do so more frequently than not.
The pleura is a sac which consists of the lungs and a thin membrane called the mesothelium which emit a fluid that allows the lungs to contract and spread while we are breathing. When asbestos particles are inhaled, the fibers inside the lungs are enlarged, and because these fibers have sharpness and microscopic size, the fibers could possibly go through the walls of the lung, entering the pleural cavity. As they move from the lung into the pleural cavity, the sharp strands shred and injure the mesothelium, damaging it and can cause cancer.
When asbestos fibers occupy the pleural cavity, cancerous tumors may enlarge which thicken the pleural fluid and restrain free lung movement. Over a long period of time, usually two or three decades, asbestos fibers cause changes in the pleural cells, which can result in scarring of the lungs, and finally the development of tumors. Tumors are able to tighten the lungs and compress on the ribcage or other organs causing agonizing pain.
When pleural cells turn into cancerous, they are no longer controlled by the mechanisms that regulate division of normal healthy cells. They begin to divide continuously, and this causes thickening of pleural membranes. As a result, lung capacity is decreased, and fluid starts to build up between pleural layers.
Since the lungs are responsible for re-oxygenating blood, if the cancer spread directly into the lungs, the cancerous cells possibly can spread into other parts of the organ through the bloodstream.
Doctors as well as scientists still do not have any idea why asbestos fibers are capable to bring the mesothelium to transform into cancer. However, as more asbestos cases are informed, doctors and scientists are discovering more and more about this ravaging condition. It is believed that even a single fiber can initiate the cascade of events that cause mesothelioma.
Since the time it takes for the asbestos particle to turn cancerous is very great - approximately between 20 to 30 years (sometimes longer) - it is not an easy job to spot, making it impossible for people to become conscious that they have been affected until it is too late.
Peritoneal Mesothelioma - affects the abdomen
Peritoneal mesothelioma is much less frequent than pleural mesothelioma. It accounts for about 10 to 20% of mesothelioma cases.
Peritoneal mesothelioma is a cancer in the lining that enfolds the abdomen or stomach, called the peritoneum. The peritoneum cells are cells that yield a lubricating fluid for the stomach and intestine to move and function properly. Once these organs are able to move properly, smooth digesting and processing food happen. A failure in the peritoneum can cause severe and injuring consequences.
Peritoneal mesothelioma affects the thin cell membrane called the peritoneum. This collection of cells surrounds the gastrointestinal tract and provides lubrication for the stomach and intestines to move so that they may function properly. These organs must be able to move properly in order to properly digest and process food and a failure in the peritoneum can result in severe and injuring consequences.
There are two main theories concering the method by which exposure to asbestos leads to the development of peritoneal mesothelioma:
1. Asbestos fibers are breathed in, and move to the peritoneal membrane through the lymphatic system.
2. Asbestos fibers are ingested, and these fibers work their way from digestive organs into the peritoneal membrane.
Apart from how asbestos fibers actually come into the peritoneal layers, once they do enter the membrane, the body loses the ability to eject them. The fibers become trapped in the peritoneal membrane, and more than a period of two or more decades, they cause certain changes in the mesothelial cells of the peritoneum.
The precise way in which asbestos fibers affect changes in these mesothelial cells is unsure. One theory states that asbestos fibers cause long-term irritation and inflammation that eventually causes mesothelial cells to be cancerous. Once cells become cancerous, they cannot control their own growth and division. Cancerous mesothelial cells divide and grow without restriction, and this unregulated cell growth causes thickening of the peritoneum, and the build-up of fluid in the peritoneal layers. Over and over again, as cancerous cells keep on dividing, tumors appear.
When peritoneal mesothelioma originates in the abdomen, it frequently metastasizes to other organs in area including the bowel, spleen or liver. Severe abdominal pain is the most frequent complaint that patients portray to their physicians. There may be a discomfort level with fluid build up in the stomach as well. The survival rate is even worse for patients diagnosed with peritoneal mesothelioma. Averagely speking, patients generally survive within ten months only from time that they first started experiencing the symptoms noted above.
Pericardial Mesothelioma - affects the heart
Pericardial mesothelioma is the least frequent type of malignant mesothelioma. Only 5 to 15% of mesothelioma cases are pericardial mesothelioma.
Pericardial mesothelioma affects the pericardium, a membrane structured by mesothelial cells that bound the heart and gives protection and support to this organ. The membrane consists of two disctinct layers - an outer layer called the parietal layer (called the heart sac or theca cordis), and an inner layer known as the visceral layer (called the epicardium). The parietal layer is part of a larger membrane that lines the entire chest cavity, while the visceral layer is the pericardial membrane that lines the heart.
It was already discovered long ago that pleural mesothelioma, which affects the lining of the lungs, is caused by inhalation of asbestos fibers. Nevertheless, doctors and scientists still cannot explain very well the way in which asbestos triggers the development of pericardial mesothelioma.
Some experts consider that inhaled asbestos fibers pass through via the bloodstream from the lungs to the heart. Nonetheless, there is no conclusive proof to support such theory.
What is discovered is that asbestos fibers somehow turn out to be lodged in the pericardial membranes that envelopes the heart. Once this happens, the body undergoes severe difficulty in removing the asbestos fibers and they are able to remain stuck in the membranes. Over a long interval of time, usually twenty years or even more, the asbestos fibers cause the cells of the pericardium to experience changes that can result in cancer.
When cells turn out to be cancerous they start to divide more quickly, without the control that orders the growth cycles of normal and healthy cells.When these malignant pericardial mesothelioma cells keep on growing, they develop to thicken the pericardial membranes, and finally cause tumors to grow. The alteration in this membrane is followed by the build-up of fluid between the pericardial layers, which combined with the layer thickening and eventually the heart gets pressured
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