Cancers. Tumors of the lining of chest, pleura, and abdomen, peritoneum, are called mesotheliomas. These are malignant tumors, i.e., cancers. Asbestos is the usual cause of mesotheliomas.
Cancer. Mesothelioma is a malignant tumor of the lining epithelium of visceral organs. Commonly the pleura, which is a lining epithelium in the chest that covers the lung, is affected. The etiology is unknown for this disease but usually associated with "asbestos exposure". You may want to get more information in the internet about this disease.