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What is Mesothelioma?

Mesothelioma, sometimes referred to as meso or mesothelioma cancer, is a form of cancer most often caused by asbestos, that affects the smooth lining of the chest, lungs, heart, and abdomen. The layer of tissue surrounding these organs is made up of mesothelial cells, hence the name mesothelioma.

For more information on the risk factors associated with the development of mesothelioma, as well as the related risks of asbestos exposure, visit the Causes of Mesothelioma Page.

Main Types of Mesothelioma

Mesothelioma forms a solid tumor that begins as a result of insult to the tissues caused by asbestos particles. These penetrate into the pleural cavity of the chest or into the abdomen. Mesothelioma most often forms in the pleural cavity of the chest or into the abdomen. The most common type of mesothelioma is pleural mesothelioma.

  • What is pleural mesothelioma? - This most common form of mesothelioma accounts for approximately 2,500 - 3,000 cases a year in the United States. This disease affects the pleura, which is the thin balloon shaped lining of the lungs.
  • What is peritoneal mesothelioma? - This form of meso is discovered in approximately 250 cases a year, and occurs in the peritoneum – the lining of the abdominal organ.
  • What is pericardial mesothelioma? - This type of mesothelioma cancer only accounts for around five percent of the newly diagnosed cases a year, and occurs in the pericardium – the lining of the heart.

More Mesothelioma Information: Development of Disease and Progression of Symptoms

In its early stages, mesothelioma cancer is difficult to detect as it may start with a thickening of the pleural rind, or fluid which can be associated with many other conditions. This rind is normally thin and smooth in the non-diseased state. In time it begins to demonstrate progression forming a more pronounced irregular rind and nodules which coalesce into a crust that compresses and invades into adjacent structures compromising lung and cardiac function.

In the abdominal cavity it can invade into the liver and bowel rendering the patient inoperable. Peritoneal mesothelioma is often found coating the omentum described sometimes as a salt like sand like particles too numerous to count and impossible to remove without sacrificing the entire omentum. Involvement of the ovaries and fallopian tubes is not uncommon in women and often mesothelioma is confused with ovarian cancer. Once vital organs are involved or disease identified outside of the operative field, surgery is no longer an option and patients are referred to chemotherapy or clinical trials.

Pleural epithelial mesothelioma on chest wall and lung.Figure E: Right pleural epithelial mesothelioma on chest wall and lung. Photo courtesy K. Brauch

For the vast majority of patients, as the tumor mass grows, once subtle symptoms will give way to weight loss, cough, respiratory infections, fatigue, shortness of breath, digestive and bowel problems and pain in the chest or abdomen, depending upon whether it is pleural or peritoneal. It may begin to weep fluid into the  intracavitary space. In the chest cavity this is called an effusion and it fills the space where the lobes of the lung reside, next to the lining of the chest cavity, and often spreads into the area surrounding the heart creating symptoms similar to those observed in congestive heart failure. In peritoneal patients it is called ascites and it fills the abdomen bathing the visceral organs with this malignant fluid.

Epithelial mesothelioma on the diaphragm.

Figure F: Epithelial mesothelioma on the diaphragm.

The symptoms of mesothelioma gradually become more noticeable, prompting the patient to seek a medical consultation. By this time the progression of the disease may already be too advanced as the tumor may have spread to the lymph nodes and/or begun to metastasize to remote organs of the body like the brain, spleen, liver or kidneys. Metastatic mesothelioma is considered late stage and incurable, given the current state of treatments. It is widely reported that only 10-20% of patients with pleural mesothelioma are diagnosed early enough for surgical intervention, the rest are referred on to palliative care. No such figures have been reported in peritoneal mesothelioma.

Want to learn more about mesothelioma and the link between asbestos and cancer? Contact the Meso Foundation for more information, news and support.