Introduction to Mesothelioma

What is Mesothelioma?

Malignant pleural mesothelioma (MPM) is a cancer of the cells that make up the pleura, a thin protective sac that covers the lungs and lines the chest wall.

In about two-thirds of all mesothelioma patients, the disease develops in the pleural mesothelium, or lung lining. In one-third of patients, it develops in the abdomen. Mesothelioma rarely occurs elsewhere, such as around the heart or in the reproductive organs.

Mesothelioma is primarily a locally invasive cancer, but it may spread to distant organs late in the disease. Usually only one side of the chest is involved with no preference for either side. Fewer than five percent of patients have the disease on both sides. Mesothelioma occurs in men with much greater frequency than in women.

Mesothelioma is a rare cancer, with approximately 3,000 new cases diagnosed yearly in the U.S. The time lag between exposure to asbestos and development of the disease ranges from 15 to 50 years.

At the time most mesotheliomas are diagnosed, the pleural surface is studded with many small nodules. As time progresses, the nodules combine to form a continuous solid tumor that encases the lung, like the rind of an orange, interfering with breathing. Symptoms in patients with mesothelioma generally include shortness of breath, cough, chest pain, and weight loss.

Potential Causes for Mesothelioma

The association between mesothelioma and asbestos is well established. Approximately 80 percent of patients know that they have been exposed asbestos. People at high risk include those who have handled asbestos on the job, such as workers in mines, mills, or shipyards. The risk extends to those living in surrounding communities and to family members who may be exposed through contact with tools and clothing.

The absence of asbestos exposure in the remaining 20 percent of patients has prompted some experts to argue for a genetic predisposition. Even with known asbestos exposure, the estimated lifetime risk of developing mesothelioma is only 5-7 percent. This supports the theory that other environmental or genetic factors may be involved. Another associated risk factor is radiation. Radiation-induced malignant mesothelioma appears to have the same prognosis as asbestos-related mesothelioma.

There is no cure for mesothelioma, but the outlook often depends on how early it is diagnosed and how aggressively it is treated. Prompt medical evaluation and aggressive treatment can lead to prolonged survival or successful treatment of symptoms.