- Types of Mesothelioma
- Location of Cancer
- Histological Subtypes
- What Causes Mesothelioma
- Tragedy of Mesothelioma
- Statistics Summary
This type of cancer is diffuse malignancy that spreads itself throughout a tissue area as an invasion of a large number of smaller masses, unlike other cancers that are characterized by a single, solid tumor mass. This diffuse nature has important implications for how treatment, and complete surgical extraction of the cancer is difficult.
Types of Mesothelioma
The mesothelium, the membrane that surrounds many of the body’s vital organs, is where the cancer develops when asbestos is inhaled or ingested. The membrane secretes a lubricating fluid that provides easy movement of the organs within the body. When the mesothelium becomes cancerous, it is called mesothelioma.
There are multiple forms of the cancer when it affects the mesothelium. The form is determined by the location in which the tumor begins, known as its origin site, and the type of cells that the tumor invades, known as its histological subtype. Each type may require a different treatment.
Location of Disease
The most common form, as many as eighty percent of all diagnoses, is pleural mesothelioma, where the cancer attacks the pleural tissue surrounding the lung. The pleura proximity to the lung is the reason many people mistakenly think of this form as lung cancer, which it is not. Although the cancer can spread (“metastasize”) from the pleura into the lung, the origin site is the actual pleural tissue surrounding the lung – not the lung itself. There are many differences between mesothelioma and lung cancer.
The next most common type is peritoneal mesothelioma, which develops in the majority of other cases. While pericardial and tunica vaginalis are also possible forms of the disease, they are very rare.
Besides the location in which the tumors form, the other identifying factor in the diagnosis of mesothelioma is the histological subtype of the cancer. This refers to the type of cells that the tumors invade. There are three histological subtypes: epithelioid, which attacks epithelial cells, sarcomatoid, which attacks sarcomatous cells, and bi-phasic, where the tumor attacks both epithelial and sarcomatous cells. The identification of the proper subtype is an important diagnostic factor because it greatly affects the disease prognosis. Epithelioid has the best response rate for treatment, while sarcomatoid has the worst.
Mesothelioma and Asbestos
While a rare disorder in the general population, mesothelioma is not rare among individuals exposed to asbestos. There are two to three thousand new diagnoses of the cancer every year.
Exposure to asbestos is the only confirmed cause of mesothelioma, and most people diagnosed with the disease were exposed to asbestos in the workplace and were never told of its dangers or given proper protective gear. Others were exposed through family members who brought asbestos home on their clothes or through home renovation projects. Unlike many other predominantly pulmonary-related cancers, cigarette smoking has no known causative effect on its incidence, although asbestos workers who smoke do have a much greater likelihood to develop lung cancer, even more so than regular smokers who don’t work with asbestos.
Tragedy of Mesothelioma
The great tragedy of this deadly disease is that it was preventable. Many of the corporations that manufactured and profited from the sale of asbestos-containing products were aware of the hazards of asbestos. These companies did not warn of the risks or protect workers. It was their legal duty to know about their products and to test them for any potential hazards. If a potential hazard did exist, the company had a responsibility to warn workers of these hazards. In many cases they hid the knowledge they had in order to protect themselves from liability or from having to find a new business model. The result is that many workers have unnecessarily developed mesothelioma.
Source: Global mesothelioma deaths reported to the World Health Organization be tween 1994 and 2008
Mesothelioma Statistics Summary
- Research shows more than 20 million people in the United States are at risk of developing malignant mesothelioma due to asbestos exposure.
- More than 100,000 U.S. citizens are expected to die of mesothelioma during the next 40 years.
- 18,068 Americans died from malignant mesothelioma between 1999 and 2005. 14,591 of the deaths occurred in men.
- Today, malignant mesothelioma is responsible for approximately 3,000 deaths per year in the United States and 5,000 deaths in Western Europe. However, mortality rates are expected to increase by 5-10% per year in most industrialized countries until about 2020.
- An estimated 1.3 million construction and general industry workers potentially are being exposed to asbestos.
- The World Health Organization estimates that asbestos causes approximately half of all deaths from occupational cancer, and 125 million people worldwide are exposed to asbestos in the workplace.