The term Mesothelioma is used to describe a cancerous tumor that involves the “mosothelial” cells of an organ, usually the lungs, heart or abdominal organs. The most common type is pleural mesothelioma, a very agresive form of lung cancer. The “pleura” is a thin membrane found between the lungs and the chest cavity, which serves as a lubricant to prevent the lungs from chafing against the chest walls. When pleural mesothelioma cancer spreads, the cells of the mesothelium become abnormal. These malignant cells begin to divide and spread without order and can begin to affect organs and tissues in the immediate area. This often leads to complications in the surrounding organs.
There are two types of Pleural Mesothelioma, diffuse and malignant (cancerous), and localized and benign (non-cancerous). Benign mesotheliomas can often be removed surgically, are generally not life-threatening, and are not usually related to asbestos exposure. Malignant mesotheliomas, even though rare, are very serious and require more aggresive treatments.
The most serious type of mesothelioma, diffuse malignant mesothelioma, is a cancer of the cells that make up the pleura or lining around the outside of the lungs and inside of the ribs and accounts for about 75% of all cases. Fluid build-up from the pleural effusion can generally be seen on a chest x-ray and heard during a physical examination, but a firm diagnosis of mesothelioma can only be made through a biopsy and pathological testing. This is important because there are also benign pleural effusions and other tumors that have a similar appearance to mesothelioma. Diagnosing mesothelioma can be quite difficult; it requires special lab stains, and often considerable experience by the pathologist interpreting the results.
The spread of the tumor over the pleura causes pleural thickening. This can reduce the flexibility of the pleura and encase the lungs in an increasingly restrictive girdle. With the lungs restricted, they get smaller and less functional, and breathing becomes more difficult. At first a person with mesothelioma may be breathless only when he or she exercises, but as lung function drops, he or she can become short of breath even while resting.
The tumor spreads by direct invasion of surrounding tissue. As it spreads inward it can compress the lungs. As the tumor spreads outward it can invade the chest wall and ribs, and this can be extremely painful.
Current medical science does not know exactly how and why, at a cellular level, asbestos fibers cause mesothelial cells to become abnormal (malignant or cancerous.) Thus it is not known whether only one fiber causes the tumor or whether it takes many fibers. It seems that asbestos fibers in the pleura can start a tumor as well as promote its growth; the tumor does not depend on any other processes for its development.
Unfortunately there is as yet no known absolute cure for malignant mesothelioma. The prognosis depends on various factors, including the size and stage of the tumor, the extent of the tumor, the cell type, and whether or not the tumor responds to treatment. The treatment options for people with mesothelioma have improved significantly, especially for those whose cancer is diagnosed early and treated vigorously.
Some of the treatments currently available for pleural mesothelioma include:
•Intra-operative photodynamic therapy