|Pleural cancer (malignant mesothelioma) refers to abnormal growth of the tissue that lines the chest wall and envelops the lungs (pleura). Although most pleural cancers are metastatic (secondary cancers from other organs or tissues), primary cancer of the pleura may either present as diffuse malignant mesothelioma or localized mesothelioma. Localized mesothelioma, known as localized fibrous tumor of the pleura (LFTP), has both benign and malignant forms that occur at a ratio of 7:1 (Meziane).|
Mesothelioma is characterized by numerous small lumps (nodules) that cover the pleura. Eventually, these nodules spread and form a sheet-like thickening that encases and compresses the lungs. It can also spread to the esophagus, ribs, vertebra, and peritoneal cavity. Individuals who develop mesothelioma have usually had exposure to asbestos, which was commonly used in mining, shipbuilding, construction, and the manufacturing of textiles and insulation before governmental legislation restricted asbestos exposure in the US.
Localized mesothelioma, or LFTP, is rarer than malignant mesothelioma and is often harmless (benign). LFTP may arise from tumors originating in the abdominal (visceral) pleura that project into the pleural cavity surrounding the lungs. They may cause fluid to escape from blood vessels into the pleural cavity because of rupture or seepage (pleural effusion).
Malignant mesothelioma is staged from I to IV, with IV being the most advanced disease. Stage I is cancer that remains localized in the pleura and lung, stage II is cancer that has invaded the chest wall or mediastinum and has metastasized to nearby thoracic lymph nodes, stage III is cancer that has invaded the diaphragm and peritoneal cavity or has metastasized to distant lymph nodes, and stage IV is cancer that has metastasized to distant locations.
Risk: The major risk factor for malignant mesothelioma is exposure to asbestos; at least 50% of exposed individuals will develop the cancer (Tan). However, onset of mesothelioma does not usually occur until 35 to 40 years after the individual has been exposed to asbestos (Dee). Smoking increases the risk of mesothelioma for those working with asbestos ("Detailed Guide"). Mesothelioma is most commonly diagnosed in individuals between the ages of 50 to 70 after a long latency period, and affects 4 times more men than women (Khan; Dee).
Localized mesothelioma (malignant LFTP) has no association with asbestos, and has no known cause. LFTP is most commonly diagnosed between the ages of 60 to 80, with men and women equally affected (Meziane).
Incidence and Prevalence: Malignant mesothelioma and LFTP are rare diseases; the incidence of mesothelioma is less than 5% of all pleural malignancies (Khan). It is estimated that 8 million individuals in the US have been exposed to asbestos, and there are about 2,000 to 3,000 new asbestos-related cancer cases diagnosed annually in the US (Tan). Only 1 in 1 million individuals without exposure to asbestos will be diagnosed with malignant mesothelioma (Dee).
Source: Medical Disability Advisor