Merck Manual

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Carrie A. Redlich

, MD, MPH, Yale Occupational and Environmental Medicine Program Yale School of Medicine;

Efia S. James

, MD, MPH, Yale School of Medicine;

Brian Linde

, MD, MPH, Yale Occ and Env Medicine Program

Reviewed/Revised Nov 2023

Mesothelioma is a rare cancer of the mesothelium, which is the thin, transparent membrane that lines the pleura and covers and lines the inside of the chest wall and abdomen.

  • The most common symptoms are persistent chest pain and shortness of breath.

  • A chest CT scan and pleural biopsy are used to make the diagnosis of mesothelioma.

  • Mesothelioma is treated with surgery, chemotherapy, and/or radiation therapy.

The term mesothelioma (sometimes called malignant mesothelioma) refers to a primary cancer of the mesothelium. Mesothelioma is almost always caused by asbestos exposure. Asbestos is a family of naturally occurring silicates (minerals) whose heat-resistant and structural properties are useful in construction and shipbuilding materials, automobile brakes, and some textiles.

The risk of mesothelioma depends on the level of asbestos exposure. However, cases are known to occur at low levels of exposure. Mesotheliomas usually develop about 30 to 50 years after exposure. Risk is independent of whether the person has a history of smoking.

In addition to occupational exposure, mesothelioma can occur as a result of para-occupational (or take-home) exposure to asbestos. Asbestos can be found in low levels in the air, water, and soil, but this low level of environmental exposure is not a significant contributor to human disease.

Did You Know...

  • Smoking is not a cause of mesothelioma.

Symptoms of Mesothelioma

Persistent pain in the chest and shortness of breath are the most common symptoms of mesothelioma. If mesothelioma spreads to the chest wall or other nearby structures in the chest, the person may have severe pain, hoarseness, difficulty swallowing, or swelling of the abdomen.

Diagnosis of Mesothelioma

  • A history of exposure to asbestos

  • Chest imaging (x-ray, computed tomography)

  • Pleural fluid analysis or pleural biopsy

The diagnosis of mesothelioma can be challenging for doctors.

Usually a sample of fluid from the pleural space is analyzed (pleural fluid cytology), and a sample of tissue from the pleura (pleural biopsy) is examined to look for characteristic changes due to mesothelioma.

Screening for mesothelioma, which is testing to diagnose people who have been exposed to asbestos but have no evidence of mesothelioma, is not recommended.

Treatment of Mesothelioma

  • Supportive care

  • Chemotherapy and immunotherapy

The major focus of treatment is supportive care and relief of pain and shortness of breath. Removing excess fluid between the layers of the pleura can improve symptoms and quality of life.

Doctors may consider surgery in people with early-stage disease. In more advanced disease, surgery has been used for debulking or attempting to remove all visible disease.

Radiation therapy can be used to reduce tumor bulk and as a palliative measure to relieve symptoms.

Chemotherapy has shown limited benefit, with little impact on long-term survival. Immunotherapy (for example, using checkpoint inhibitors such as tremelimumab, pembrolizumab, nivolumab, or ipilimumab) or the combination of chemotherapy and immunotherapy has shown some promise in slowing progression and improving short-term survival but has had limited impact on long-term survival.

Prognosis for Mesothelioma

Prognosis remains poor despite new treatment approaches such as immunotherapy. Most people live for 6 to 18 months after mesothelioma is diagnosed.

Prevention of Mesothelioma

Mesothelioma and other diseases caused by asbestos inhalation can be prevented by minimizing asbestos dust and fibers. Despite lower asbestos exposure today, mesotheliomas are still occurring in people who were exposed as many as 30 to 50 years ago.

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