Causes of Mesothelioma

Mesothelioma is a highly aggressive cancer that is difficult to both diagnose and treat. Between two and three thousand cases of malignant mesothelioma are diagnosed each year in America, and these figures are projected to increase throughout the next decade.

What Causes Mesothelioma?

An overwhelming body of scientific and medical evidence has proven that malignant mesothelioma is caused by asbestos exposure. Currently, there is no other proven cause for this disease.

Asbestos is a naturally-occurring fibrous mineral that was widely used in industrial, commercial, and domestic products throughout the twentieth century. Asbestos was touted for its durability, fire resistance, and excellent insulating properties, and was used in several thousand different manufactured "asbestos products," including construction materials, household appliances, and brake linings. Because asbestos use was so widespread, millions of Americans have been exposed to the toxic material, which has led to the development of malignant mesothelioma among thousands of Americans.

How Does Asbestos Exposure Cause Mesothelioma?

Internal organs and body cavities are covered by a thin tissue membrane called the mesothelium. This lining covers the thoracic cavity (where it is called the pleura), the heart sac (where it is known as the pericardium), and the abdominal cavity (where it is called the peritoneum). The mesothelium offers both support and protection for organs and body cavities and provides a source of lubrication that helps organ function and health.

Mesothelioma develops in the linings of organs and body cavities, typically in the pleura, pericardium, or peritoneum. In very rare cases, mesothelioma may develop in the lining of the testicles, known as the tunica vaginalis.

The exact method by which asbestos causes mesothelioma is still being researched, but medical professionals offer four different theories:

• Asbestos causes irritation and inflammation of mesothelial cells, which results in irreversible scarring, cellular damage, and eventually cancer.
• Asbestos fibers enter cells and disrupt the function of cellular structures that are essential for normal cell division, causing cellular changes that lead to cancer.
• Asbestos causes the production of free radicals. These molecules damage DNA, and cause cells to mutate and become cancerous.
• The presence of asbestos causes cells to produce oncoproteins. These molecules cause mesothelial cells to ignore normal cellular division restraints, and this can lead to the development of cancer.

The element that ties each theory together is the fact that asbestos results in cellular damage, which causes cells to lose control over their own cycles of normal division and begin dividing uncontrollably. Healthy cells follow cycles of cell division that ensure tissues and organs do not grow beyond normal size - in cancer cells, these restraints are lost.

In cases of mesothelioma, the result is that membranes in the affected location begin to thicken, and fluid builds up in the spaces between membrane layers. As cancer cells continue to divide and pile on top of one another, tumors begin to form. The uncontrolled division of cancer cells results in the impaired function of the body's organs and systems (primarily due to factors such as internal pressure caused by the growth of tumors, and the reduction of essential nutrients for organs).

Are There Any Other Causes of Mesothelioma?

Cancer doctors and research scientists have not been able to directly prove any other causes of mesothelioma other than asbestos exposure. They do know, however, that smoking can aggravate a less serious asbestos-related disease, such as asbestosis, and prompt the formation of tumors and the onset of mesothelioma. Additionally, asbestos exposure and smoking has a synergistic affect that can increase a person's risk of developing lung cancer by as much as 84 times or more. For this reason, those who have been exposed to asbestos on a regular basis are highly advised not to smoke.