About Mesothelioma

Mesothelioma is a rare form of cancer that develops in the mesothelial cells. These cells are tissue that surround or line the lungs, heart, and stomach. The mesothelial cells protect these organs by producing a lubricating fluid that allows these organs to move smoothly.

Malignant mesotheliomas arise from the cells that line the surface of the pleura or the peritoneum. Eighty percent of these tumors are pleural in origin. Malignant mesotheliomas are rare, with an incidence of one to three cases per 1 million persons per year in the general population. Approximately 2000 new cases are diagnosed each year.

The relationship between asbestos exposure and malignant mesothelioma was established in 1960. The latency period between exposure and tumor development has usually been 30 years or more.

The incidence of malignant mesothelioma has been highest in persons with heavy occupational exposure to asbestos, such as shipyard workers. However, malignant mesothelioma can occur in the absence of any known asbestos exposure. No history of such exposure has been noted in about one-third of cases, and the etiology of these cases is usually unknown. Some cases of mesothelioma have been diagnosed in family members of asbestos workers and people who reside near asbestos mines. Cigarette smoking is not considered a risk factor for malignant mesothelioma.

The patient with malignant mesothelioma of the pleura may have symptoms of dyspnea (shortness of breath)and pleuritic chest pain (pain with breathing), with malaise and weight loss. A large pleural effusion is often seen on the radiograph. This effusion which is a collection of fluid between the lungs and the chest is frequently bloody, and the hyaluronic acid level may be elevated. Associated parenchymal fibrosis (asbestosis) is rare in pleural mesothelioma but appears to be more common in peritoneal mesothelioma.

Malignant mesothelioma can be very difficult to diagnose, although medical advances have made it somewhat easier. A CAT scan or an MRI scan may show the cancer; If the cancer is in the chest, a surgeon can make a small incision between two ribs and insert a tiny instrument with a light and a camera inside, and take samples with this instrument. If the cancer is in the abdomen, a similar procedure, called a peritoneoscopy can be performed. Actual open biopsy is only necessary if there is no other way to obtain tissue,

There is no 100% effective treatment for malignant mesothelioma. Complete surgical resection is not possible in most cases. In many cases, part of the pleura and part of the tumor can be removed, surgery which decreases symptoms. The tumor encases the lung in a bulky, lobulated mass that invades the fissures and, eventually, the diaphragm and the chest wall. Average survival is one to two years. Except in rare cases, chemotherapy and radiation therapy have not been useful. Despite these facts however, there have been patients who have lived longer because of emerging treatments, and earlier diagnosis.

Anna L. Kaplan, M.D.