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).