Malignant mesothelioma is a primary neoplasm of the mesothelial lining of the pleural (80%) or peritoneal cavity (20%). This disease is linked conclusively to prior exposure to asbestos. The incidence of malignant mesothelioma is expected to rise until the year 2000, and will remain substantial for the next 3 decades. The risk of developing mesothelioma in an individual with occupational asbestos exposure is approximately 10% over a lifetime canadianneighborpharmacy.com. The incidence of mesothelioma is increasing steadily in many countries, including Canada and the United States.’ In addition, the incidence of mesothelioma is on the rise in women and those with no history of asbestos exposure.
Several staging systems have been proposed for malignant mesothelioma, but the disease is frequently staged using the approach proposed by Butchart et al. Recently, the International Mesothelioma Interest Group proposed a new staging system that describes in more detail the extent of the primary tumor, and emphasizes the significance of nodal metastases with regard to outcome and prognosis. In most cases, mesothelioma is a diffuse disease at the time of diagnosis. The tumor spreads locally, often invading thoracic structures such as chest wall, pericardium, myocardium, and great vessels. Distant blood-borne metastases usually occur very late in the disease but can be detected in 50 to 80% of cases at autopsy. The median survival for patients with mesothelioma after diagnosis is between 12 and 18 months. Therapy for mesothelioma includes surgery, irradiation, and chemotherapy, employed individually or in combination. To date, these interventions have been generally ineffective. Surgical resection allows the removal of the bulk of the tumor but often fails to eradicate the disease. The use of radiation is limited because of the large volume of the tumor and the radiosensitivity of adjacent intrathoracic organs. Thus, adequate localization of the involved pleura is important for surgical intervention and radiation therapy planning in these patients.