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Pleural Mesothelioma
Mesothelioma is a form of cancer that affects the mesothelium. The mesothelium is a membrane that covers many of the body’s internal organs, such as the lungs and heart, and also lines the chest, the abdomen, and the area around the heart. The mesothelium is composed of mesothelial cells; when these cells become cancerous, mesothelioma develops.
There are several types of mesothelioma: pleural mesothelioma, which affects the chest wall lining and the lungs; peritoneal mesothelioma, which affects the abdomen; pericardial mesothelioma which affects the sac surrounding the heart; and, most rarely, tunica vaginalis mesothelium, which affects a layer of tissue surrounding the testis in males. By far, the most common form of mesothelioma is pleural mesothelioma, which accounts for up to 75% of all cases of the disease (1).
The most common cause of pleural mesothelioma is exposure to asbestos, a term which describes a group of six naturally-occurring minerals. From the late 1800’s through the late twentieth century, asbestos was widely used in industrial and construction processes, as well as in the production of many household products. Known for its cloth-like qualities, its strength and its resistance to heat and fire, asbestos offered many obvious advantages in production processes. However, it also posed great risks to those who came into contact with it, a fact which was discovered and documented by the 1920’s. For decades, industries and employers ranging from steel and shipbuilding companies to the US Navy knew about the risks of asbestos exposure, but withheld this information from workers and failed to provide adequate safety equipment. It was not until 1989, however, that the Environmental Protection Agency banned most uses of asbestos in the United States. Limited, regulated use continues today in the United States.
Asbestos exposure occurs when its fibers become airborne and are either inhaled or swallowed. Fibers become lodged in tissue, particularly in the lungs or chest wall. Over the years, these fibers act as aggravating agents and can ultimately lead to the development of mesothelioma. This explains how pleural mesothelioma begins. Once exposure occurs, an individual will always be at risk. It may take anywhere from fifteen to fifty years for the disease to develop after an initial exposure.
Early symptoms of pleural mesothelioma may at first seem like those associated with common ailments and for this reason, it often takes up to three months after the onset of symptoms for an individual to seek medical care. Lower back pain and/or discomfort in the side of the chest, are very common early symptoms of pleural mesothelioma. Some people may experience cough, sweating, fever, exhaustion, weight loss and difficulty swallowing. People may also cough up blood and experience swelling of the face and arms, hoarseness, and weakness.
Pleural mesothelioma can be diagnosed through a physical exam, diagnostic imaging and tissue and fluid samples. Pleural mesothelioma can affect the lining of the chest wall or of the lungs. As it advances, it can spread to lymph nodes, from one side of the chest wall lining to the other, and to other parts of the body. The spread of the disease is called metastasis.
Once an initial diagnosis is made, a process called “staging” is used to describe the size, location, and extent of the primary tumor. As the disease progresses, “staging” is used to track changes. There are three primary, established staging systems. These are: The Butchart System is based on the primary tumor’s size; the TNM System refers to the size of the primary tumor (T), whether or not the cancer has spread to nearby nodes (N) and whether it has metastasized distantly (M); and the Brigham System stages the cancer based on whether the tumor can be removed by surgery (resected) and whether or not lymph nodes are affected (2).
The next step is for a patient and his or her physician to determine the best course of treatment for him or her. This decision should be based on the patient’s wishes, the stage of the disease and factors such as the patient’s general health, age, weight, and gender.
The most common and established forms of treatment for pleural mesothelioma are surgery, chemotherapy and radiation. Examples of these types of treatments are described here. There are two general types of surgery used to respond to mesothelioma: palliative surgery is used to alleviate the discomfort caused by symptoms such as shortness of breath related to fluid in the pleura pushing against the lungs; and curative surgery is used to slow or stop the growth of the disease and to extend a patient’s life.
To reduce shortness of breath, a doctor can perform a thoracentsis to drain this fluid. In some cases, the doctor will also inject either talc or drugs which create scar tissue into the chest to prevent further fluid from entering the chest cavity. This technique is called a pleurodesis and is effective for a time. However, if this procedure is performed frequently, it can actually increase the chance of fluid returning to the chest cavity. However, the risks do not typically outweigh the increased comfort that a pleurodesis provides.
Chemotherapy uses drugs that kill cancer cells to treat mesothelioma. It can also be used to destroy cancer that comes back or that has metastasized (spread) to other parts of the body. The names of some of the most commonly used drugs are cisplatin, gemcitabine, coramsine, and endostatin. Drugs may be administered individually or in pairs.
Radiation therapy is administered to kill cancerous cells. There are a number of ways to administer radiation therapy, either internally or externally. Internal radiation is delivered into the body and external radiation is provided by a linear accelerator, or by a type of machine that has as its radiation source a radioactive substance. However, radiation therapy is not considered the most effective treatment for mesothelioma (3).
Pleural mesothelioma is considered treatable but not curable. Treatment has been shown to reduce the symptoms and discomfort caused by pleural mesothelioma. In some cases, it also extends an individual’s lifespan.
- American Cancer Society. “What Is Malignant Mesothelioma?” 19 October 2007.
Accessed: 16 August 2007. - Cancer Help, UK. “The Stages of Mesothelioma.” 13 April 2007.
Accessed: 16 August 2007 - American Cancer Society. “Detailed Guide: Malignant Mesothelioma, Radiation Therapies.” 19 October 2006.
Accessed: 16 August 1 2007.