Asbestos Lung Cancer
Asbestos lung cancer is a group of diseases related to asbestos exposure. While the term itself is technically incorrect only one of the diseases belonging to this group (asbestosis) originates in the lungs (and it is not a form of cancer) it serves as a way of classifying asbestos-related diseases that affect the lungs.
Asbestos is a naturally occurring mineral that has been mined, processed, and used for more than 6,000 years. The two most common diseases related to asbestos lung cancer are asbestosis and mesothelioma, with pleural mesothelioma being the most common form of mesothelioma. Both mesothelioma and asbestosis are associated with the inhalation of asbestos and subsequent inflammation caused by the lodging of asbestos in the lungs.
Malignant mesothelioma is a rare type of asbestos lung cancer that results from asbestos becoming lodged in the lining of the lung. However, unlike asbestosis, which originates in the lungs, mesothelioma occurs in the serous lining, which is the lining surrounding the outside of the lungs. Another thing that distinguishes mesothelioma from asbestosis is that it leads to the growth of tumors that are malignant (asbestosis leads to the growth of scar tissue, which is benign). This means that the growths in the lungs' serous membranes related to mesothelioma are cancerous, can grow rapidly and can spread to other organs. Asbestosis, on the other hand, does not spread to other organs. When cancer tumors grow and then spread to other organs, this is called metastasis.
Mesothelioma can affect several different organs in the body, not just the lungs. When mesothelioma occurs in the lungs, it is called pleural mesothelioma; when it occurs in the heart lining it is called pericardial mesothelioma; and when it occurs in the abdomen it is called peritoneal mesothelioma. Asbestos exposure is thought to be the primary cause of all three types of mesothelioma.
The timeline between asbestos exposure and the onset of pleural mesothelioma is very long (30 to 40 years). Pleural mesothelioma can be detected by x-rays, but the diagnosis of pleural mesothelioma has to be confirmed with a biopsy. The treatments for pleural mesothelioma are similar to other cancers. They include chemotherapy, radiation therapy and surgical removal of the cancerous tissues. However, it is important to note that different types of cancers respond differently to different types of treatments. As a result, a patient's treatment plan is based on his or her individual case. Unfortunately, the disease is very aggressive, and most treatments do not slow its progression. The life expectancy of those diagnosed with pleural mesothelioma is less than a year.
Asbestosis is a disease in which asbestos fibers cause scarring of the lungs; however, it is not a type of lung cancer. This disease occurs because asbestos fibers are tiny, yet durable; when they are inhaled, the lungs' natural filtration system is unable to eliminate them from the air. As a result, asbestos is able to enter the very sterile inner reaches of the lung cavities. When asbestos fibers become lodged in the interstitium the area surrounding the lungs' air sacs (alveoli) the lungs become inflamed, which eventually leads to scarring. The timeline between the moment asbestos enters the lungs and the eventual onset of scarring can be as long as 10 years. Eventually, if enough scarring occurs in the lungs, it will be classified as fibrosis. Asbestosis is fibrosis that forms in the interstitium.
Fibrosis is defined as the development of excess fibrous connective tissue in an organ. This connective tissue cripples the areas of the lungs that it invades. Thus, when it spreads across large areas of the lungs over time, the lungs lose their ability to function properly. Similar to pleural mesothelioma, the total timeline between exposure to asbestos and the development of large areas of interstitial fibrosis can be as long as 30 or 40 years.
Asbestosis is normally detected with an x-ray showing the large fibrous growths in the lungs. Oftentimes, the initial symptom is difficulty breathing, which may be caused by the fibrous tissue that has formed, or by a pleural effusion (buildup of fluid) caused by the asbestosis. There is no cure for asbestosis, and eventually the fibrous tissue can spread throughout the lungs and make it impossible to breath. A common cause of death related to asbestosis is congestive heart failure, in which the heart becomes overworked in its attempt to push enough blood through the lungs to carry sufficient oxygen to the rest of the body.
[Page updated January 2010]