What Is Mesothelioma?

Medical Definition

From the National Center for Biotechnology Information:

Malignant mesothelioma (MM) is a tumor of the lining of the lung and chest cavity (pleura) or lining(s) of the abdomen (peritoneum) that is typically related to exposure to mineral fibers such as asbestos and erionite. Malignant mesothelioma is a neoplasm arising from mesothelial cells lining the pleural, peritoneal, and pericardial cavities.

Scope of the Problem

Over 20 million people in the US are at risk of developing mesothelioma due to asbestos exposure. MM mortality rates are estimated to increase by 5-10% per year in most industrialized countries. The incidence of mesothelioma in men has continued to rise during the past 50 years, while the incidence in women appears largely unchanged.

It is estimated that about 50-80% of pleural mesothelioma in men and 20-30% in women developed in individuals whose history indicates asbestos exposure(s) above that expected from most background settings. While rare for women, about 30% of peritoneal mesothelioma in men has been associated with exposure to asbestos.

Causes and Risk Factors

Asbestos induces DNA alterations mostly by inducing mesothelial cells and reactive macrophages to secrete mutagenic oxygen and nitrogen species. Asbestos carcinogenesis is also linked to the chronic inflammatory process caused by the deposition of a sufficient number of asbestos fibers and the consequent release of pro-inflammatory molecules, especially HMGB-1, the master switch that starts the inflammatory process, and TNF-alpha by macrophages and mesothelial cells.

Erionite is another potent carcinogenic mineral fiber capable of causing both pleural and peritoneal mesothelioma. Since erionite is considerably less widespread than asbestos, the number of mesothelioma cases associated with erionite exposure is smaller. Genetic predisposition, radiation exposure, and viral infection are co-factors that can alone or together with asbestos and erionite cause mesothelioma.