Malignant Mesothelioma (MM) is a rare form of cancer, which affects the mesothelium, the membrane covering and protecting the vital organs. The most common form of MM is pleural mesothelioma, affecting the lining of the lung cavity. Peritoneal and pericardial forms of mesothelioma, affecting the abdominal and the cardiac mesothelium, respectively, are rare. Symptoms of the disease vary, according to the mesothelium affected. Chest pain and shortness of breath (pleural MM), abdominal swelling and pain, weight loss, bowel obstruction, anemia and fever (peritoneal MM), and cough and irregular breathing patterns upon the slightest of exertion (pericardial MM) are some of the most common signs and symptoms of MM.
MM is seen to occur more often in men than in women. The single most important risk factor for developing this disease is exposure to asbestos. About 70-80% of cases of MM have a history of prolonged asbestos exposure. Unfortunately, the disease manifests its symptoms as long as 40-50 years after the exposure, in its advanced stage. Since none of the symptoms are specific to MM, diagnosis, purely on the basis of clinical features is very difficult. Complete physical examination needs to be followed up by CT and MRI or PET scans. Confirmation of MM can only be done after biopsy. Of late, the presence of Soluble Mesothelin Related Protein (SMR) in the blood is being used as a marker for the disease condition. As in most cancers, treatment involves surgical removal of the affected part of the mesothelium, followed by radiation and chemotherapy. Intracavitary chemotherapy, where the drugs are injected straight into the pleural or abdominal cavity, is also being looked into.
In patients with malignant mesothelioma, somatic mutations have been detected in the CDKN2A (Cyclin-Dependent Kinase Inhibitor 2A) gene, NF2 (Neurofibromin 2) gene, WT1 (WT1 Transcription Factor) gene, BCL10 (BCL10 Immune Signaling Adaptor) gene, and BAP1 (BRCA1 Associated Protein 1) gene. In addition to this, certain chromosomal aberrations have also been noted in MM. The most frequently observed of these is loss of material from the long arm of chromosome 14, especially involving 14q11.2-13.2, 14q22.3-24.3, and 14q32.12.