Introduction
The human body contains some important spaces or cavities that are lined by thin membranes, namely the pericardial cavity surrounding the heart, the pleural cavities surrounding the lungs, and the peritoneal cavity surrounding the gut. Mesothelioma, also known as malignant mesothelioma, is a type of cancer that arises in the cells forming the membranes that line the serous cavities of the body. This article answer the question “What is mesothelioma?”, and discuss the role of the notorious carcinogen asbestos in its occurrence, mesothelioma of the pleural cavity and of the peritoneal cavity, the symptoms of a patient with mesothelioma, the causes of the tumor, the treatment modalities that can be employed against it, the methods and investigations used to diagnose the disease, as well as the prognosis and the estimated survival rates.
Background
Serous cavities in the human body serve some important functions. The serous membranes lining them are basically like a folded sheet that envelops its specific organ. The organ is thus surrounded by a closed “bag” consisting of two layers, which contain also a thin film of clear fluid in between, which allows the two layers to slide on top of each other when the organ they surround moves. The heart, for example, is constantly beating, and it is therefore helped greatly by the presence of a serous membrane that facilitates its expansions and contractions. Like a well-oiled machine, the heart’s movement becomes smooth and effortless by virtue of its serous membrane, the pericardium.
The lungs, because of the complex process of breathing, have a different situation with regards to their serous cavity, the pleura. At rest, the pleural cavity has a negative pressure, which allows the lungs to remain inflated. When a person starts to inhale, the muscles of breathing, including the diaphragm, the intercostal muscles between the ribs, and the sternocleidomastoid all contract to expand the lungs. When this happens, the pressure within the pleural cavity becomes even more negative, pulling on the lungs and forcing the air sacs (alveoli) to open and take in air. During expiration the chest muscles relax and allow the chest wall to fall back and compress the lungs to push air out of them. In addition, the pleural cavity allows the lungs to expand and contact easily due to the presence of a slick film of fluid between the two layers of the pleura, which effectively functions as a lubricant.
Finally, the mesothelium surrounding the intestines and the other organs in the abdomen is the peritoneum. The peritoneal membrane allows nerves, blood vessels, and lymphatic vessels to reach their intended abdominal organ, and it also helps support and protect the vulnerable abdominal contents.
The mesothelium also plays a role in helping out the immune system of the body, allowing the movement of white blood cells and the synthesis of substances that aid the process of inflammation.
The most common site for the occurrence of mesothelioma in general is the pleura, which lines the lungs. Next is the peritoneum which surrounds the intestines, and then the pericardium around the heart. Very rarely it may affect the covering of the testicles in men. In the United States, the incidence is approximately three thousand patients per year.
