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What Is Mesothelioma?

Mesothelioma - Causes, Treatment and Prevention

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Updated September 14, 2013

Mesothelioma is a somewhat rare cancer, with only about 2,000 new cases diagnosed in the United States each year -- but its incidence is increasing worldwide. Sadly, most cases of this disease are related to on-the-job exposure to asbestos, and could be prevented through awareness and protective measures at work. That said, in many cases, mesothelioma does not develop until decades after asbestos exposure occurs, and many people that are diagnosed today were exposed to asbestos years ago.

What Is Mesothelioma?

Mesothelioma is a cancerous (malignant) tumor that begins in the mesothelium. The mesothelium is a membrane that lines and protects the lungs, the heart, and the abdominal cavity. There are three main types of mesothelioma:
  • Pleural mesothelioma begins in the pleura (the lining of the lungs). This is the most common type of mesothelioma.
  • Peritoneal mesothelioma begins in the peritoneum (the lining of the abdominal cavity).
  • Pericardial mesothelioma begins in the pericardium (the lining of the heart).

Causes

Most cases of mesothelioma are because of exposure to asbestos on the job. Other causes include:
  • Genetic susceptibility – Some people are more likely to develop mesothelioma than others
  • Exposure to a particular virus – A virus called simian virus 40 (SV 40) has been linked with some cases of mesothelioma
  • Exposure to radiation

Symptoms

Most people with pleural mesothelioma note shortness of breath and chest pain (especially under the ribs), but other symptoms can include:

Diagnosis

Diagnosing mesothelioma can be difficult since there are many conditions that cause similar symptoms. Your physician will first take a careful history, especially questioning you about your employment history, and then perform a physical exam. Imaging studies are often done, and may include x-rays of your chest and abdomen, CT scans, MRI scans or PET scans.

If your doctor suspects mesothelioma, she will need to schedule a biopsy. Depending upon the location of your tumor, she may recommend a thoracoscopy or video-assisted thoracoscopy (VAT), a procedure where a tissue sample is taken from the pleura, or a peritoneoscopy, a similar procedure to obtain tissue from the abdomen. If the biopsy reveals mesothelioma, further studies are then done to determine the stage of the cancer (how advanced it is).

Stages

Mesothelioma is divided into 2 primary stages:
  • Localized (Stage 1) – With localized mesothelioma, the cancer is confined to the mesothelium – the pleura with pleural mesothelioma, or the peritoneum with peritoneal mesothelioma
  • Advanced (Stage 2, 3, and 4) – Mesothelioma is considered advanced if it has spread to the lymph nodes, or other organs including the lungs

Treatment

Depending on the size and location of your tumor, and if it has spread, treatment options may include:
  • Surgery – Surgery may be considered, especially if the tumor is caught at an early stage. Types of surgery include:
    • Pleurectomy – With a pleurectomy, a portion of the pleura is removed
    • Extrapleural pneumonectomy – A portion of the pleura is removed, as well as a portion of the pericardium (heart lining), diaphragm (muscle separating the chest and abdomen) and the lung
  • Chemotherapy – A combination of a chemotherapy medication and a targeted therapy may improve survival.
  • Radiation Therapy – Radiation therapy is occasionally used as a palliative treatment for mesothelioma, a treatment that does not cure cancer, but can make you more comfortable. It may also be used after surgery to kill any remaining cancer cells.
  • Clinical Trials – Several clinical trials are in progress, evaluating new ways to treat mesothelioma.

Living With Mesothelioma

On top of the heartbreak a diagnosis of cancer brings, many people with mesothelioma lack the emotional and psychosocial support that those with other forms of cancer find readily available. In addition, medico-legal battles related to asbestos exposure on-the-job can be emotionally draining. Participating in a support group, either through your cancer center, community, or online, can help you wade through the maze of treatment options, and find camaraderie in others who are living with mesothelioma.

Prevention

The most important thing you can do to prevent mesothelioma is to use appropriate precautions if you are exposed to asbestos at work. OSHA has asbestos safety standards for individuals who may be exposed on the job. If you work with asbestos, it is important to follow these guidelines to minimize your families exposure as well. Asbestos insulation in homes is usually not a problem, unless it is damaged or disturbed by remodeling projects. If you may have asbestos insulation (homes built prior to 1950) make sure to hire a contractor certified in asbestos management before you begin any home improvement projects.

Some people who have been exposed to asbestos may want to consider CT screening for lung cancer. At this time, recommendations for screening include only those people aged 55 to 74 with a 30 pack-year history of smoking. Yet studies show that some people who have been exposed to asbestos may be at an even higher risk of developing lung cancer than heavy smokers. If you've been exposed to asbestos make sure to talk to your doctor about lung cancer screening.

Sources:

American Lung Association. Mesothelioma Fact Sheet. 2007. http://www.lungusa.org/lung-disease/lung-cancer/resources/facts-figures/mesothelioma-fact-sheet.html

Fasola, G. et al. Low-dose computed tomography screening for lung cancer and pleural mesothelioma in an asbestos-exposed population: baseline results of a prospective, nonrandomized feasibility trial – an Alpe-andria Thoracic Oncology Multidisciplinary Group Study (ATOM 001). Oncologist. 2007. 12(10):1215-24.

Hasegawa, S. and F. Tanaka. Malignant mesothelioma: current status and perspective in Japan and the world. General Thoracic and Cardiovascular Surgery. 2008. 56(7):317-23.

Hughes, N. and A. Arber. The lived experience of patients with pleural mesothelioma. International Journal of Palliative Nursing. 2008. 14(2):66-71.05/13/02.

Ramalingam, S. and C. Belani. Recent advances in the treatment of malignant pleural mesothelioma. Journal of Thoracic Oncology. 2008. 3(9):1056-64.

Roberts, H. et al. Screening for malignant pleural mesothelioma and lung cancer in individuals with a history of asbestos exposure. Journal of Thoracic Oncology. 2009. 4(5):620-8.

Weiner, S. and S. Neragi-Mandoab. Pathogenesis of metastatic pleural mesothelioma and the role of environmental and genetic factors. Journal of Cancer Research and Clinical Oncology. 2009. 135(1):15-27.

Zervos, M. et al. Malignant mesothelioma 2008. Current Opinions in Pulmonary Medicine. 2008. 14(4):303-9.

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