Diseases and Disorders
Mesothelioma is cancer of the pleura, or the inner lining of the chest, but it can also occur in the lining of the abdominal cavity. It is diagnosed in 2,500 to 3,000 patients per year in the United States, but the incidence of mesothelioma is expected to increase over the next decade due to the long latency period of its development, which can be between 15 and 50 years. It typically occurs in men more than women as a result of different rates of occupational exposure to asbestos. As the tumor grows it encases the lung and can produce fluid that compromises the function of the lung.
- Multidisciplinary team approach utilizing the latest advances in surgical techniques, chemotherapy, and radiation
- Tailored surgical treatment of either pleurectomy/decortications or extrapleural pneumonectomy, depending on the individual patient’s disease and performance status
- Access to clinical trials and drugs through USC’s participation in regional and national oncology cooperative groups
Mechanism of Disease
Mesothelioma is directly related to exposure to asbestos, a mineral that has heat-resistant and insulating properties. Asbestos was widely used in the building of ships as well as insulation material in buildings. Exposure occurs when asbestos fibers are inhaled into the lungs and then directly injure the cells surrounding the lungs. As genetic abnormalities accumulate, cancer cells form in the chest lining.
Another mechanism of mesothelioma formation is through radiation exposure to the chest. This accounts for a minority of cases, but is more commonly observed in young women who received chest radiation for previous medical conditions, such as lymphoma.
Mesothelioma is notoriously difficult to diagnose, and an adequate sized biopsy is required of the pleura or inner chest wall lining. This can require an open incision or “cut down” for exposure or it may be done with a video-assisted thoracoscopic surgery or VATS approach. These biopsies must be reviewed by an expert thoracic pathologist since mesothelioma can be confused with lung cancer. Moreover, subtyping of mesothelioma as epithelioid type, sarcomatoid type, or mixed type is important for prognosis and treatment planning.
Surgical treatment of mesothelioma is an important aspect of multimodality treatment, which also includes chemotherapy and/or radiation. Due to the uncommon nature of this disease, it is imperative to be evaluated at a center such as USC where thoracic surgeons are familiar with its treatment. There are two types of operations that are performed for mesothelioma, and operation is chosen based on the patient’s functional status and the nature of the tumor.
Pleurectomy/decortications is an operation that is intended to strip away the mesothelioma that is lining the inner chest wall and encasing the lung. This is typically done by bluntly stripping it out of the chest. In some cases it is necessary to remove the pericardium (the sac around the heart) or the diaphragm, in which case these structures are reconstructed with a synthetic mesh. It is an option in patients who have smaller or less extensive tumors, and those who do not have invasion into the lung. It is also considered for patients who are too frail to undergo an extrapleural pneumonectomy.
Extrapleural pneumonectomy is an operation in which the mesothelioma is stripped out of the chest wall and the entire tumor is removed in one piece with the lung that it is encasing, as well as the pericardium and the diaphragm. These latter structures are reconstructed with a synthetic mesh. This is a more complex operation that carries a higher complication and mortality rate, but may be necessary if the tumor is large or invades the lung. Patients must have the cardiac and pulmonary reserve to undergo such an operation, and this is factored into the decision making process.
It is generally accepted that due to the infiltrating nature of mesothelioma, surgery cannot completely remove every cancer cell in the chest. Therefore, it must be accompanied by other modes of therapy such as chemotherapy and/or radiation. Such coordinated care is a characteristic of the multidisciplinary thoracic oncology team at USC/Norris Cancer Center.
Multimodality therapy has been shown to improve outcomes in selected patients. There are no generalizable results for treatment of this disease due to the highly variable circumstances that are present in patient to patient, and outcomes depend on tumor burden, type of mesothelioma, and the type of therapy utilized. For this reason it is critical that the patient is referred to a specialized referral center like USC for evaluation by a team of surgeons, medical oncologists, and radiation oncologists.