Diffuse malignant pleural mesothelioma, or DMM, is a rare but highly aggressive type of cancer. It occurs in the thin layer of tissue, the pleura, lining the chest cavity and lungs. Once diagnosed with DMM, most patients do not survive beyond one year. This cancer is more common in men than in women, and in older people.

Most people with DMM have a history of exposure to asbestos; however, if they are not aware that such exposure occurred, they may be unaware that they are at risk. A patient with DMM typically has one or more of the following signs and symptoms: chest pain, shortness of breath, unexplained weight loss, fatigue, fever, or a cough. An x-ray usually shows that the pleural tissue around the lungs has thickened due to the development of a number of nodules or small cancerous growths. Sometimes, there may be a single large growth. When a biopsy of the cancer tissue is done, the types of cells that make up the cancer may be epithelioid, mixed, or sarcomatoid. People with epithelioid cell cancers tend to survive somewhat longer; those with sarcomatoid cancers usually have the shortest survival.

DMM is always treated as aggressively as possible. The type of treatment depends on the dominant cell type the cancer is made of, the extent of spread of the cancer, and the overall health of the person undergoing treatment. Surgery is a preferred option where the bulk of the cancer can be removed. Many anti-cancer drugs are being tried to treat DMM, with varying levels of short-term success. Radiotherapy may also be an option. A number of clinical trials are currently underway to try and find a treatment that may improve the outlook for DMM patients. However, only seven percent of people with DMM survive beyond five years.