Mesothelioma is a type of rare cancer that affects the protective sac surrounding the internal organs, which is called the mesothelium. This membrane produces a lubricating fluid which prevents friction during the normal movement of the organs—for example, the motion of the lungs during breathing. Pleural mesothelioma, which occurs in the membrane surrounding the lungs, is the most common form of this cancer.
Mesothelioma is associated with exposure to asbestos, an industrial material which was widely used in the 20th Century to provide insulation and fireproofing. When it is cut or damaged, asbestos releases a fine dust composed of microscopic, but sharp, fibers that can be inhaled and then embed themselves in the mesothelium. Since they are too small to be filtered by the lungs, they can accumulate in the body and cause cellular damage which leads to cancer.
This form of cancer can develop in one of several places, but most commonly occurs in the pleural mesothelium, which is a double-layered membrane of the lungs. The parietal layer lines the inside of the chest, and the visceral layer covers the lungs themselves. Peritoneal mesothelioma, which occurs in the lining surrounding the stomach, and pericardial mesothelioma, affecting the layer surrounding the heart, are also possible.
Pleural mesothelioma is a rare cancer, with approximately 2,500 new cases reported in the United States each year. Because it is so closely linked to asbestos exposure, those who are most at risk to develop it are those who previously worked as plumbers, electricians, boiler men, pipefitters, metalworkers, mill workers, miners, shipyard laborers, framers and sawyers. Also at risk are the families of these men, because the fibers can be carried home on clothing. More and more cases of mesothelioma, especially in women who do not have a history of working in industrial fields, are being attributed to secondhand asbestos exposure.
Mesothelioma can take years, or even decades, to become symptomatic. The long latency period means that patients may be diagnosed when they are retired from the industry which caused their illness, and that they may not even recall having been exposed to asbestos. Nevertheless, the fibers can cause a great deal of damage in the intervening years, and often mesothelioma is diagnosed only in later stages, when it has become too widespread to treat effectively.
When the symptoms do begin to surface, they can resemble symptoms of other diseases—so that the patient may think that he has a cold, the flu, pneumonia or bronchitis. This may cause a delay in diagnosis, and even doctors can be confused about the symptoms and therefore misdiagnose pleural mesothelioma. The symptoms include shortness of breath, difficulty breathing, difficulty swallowing, a persistent cough, coughing up blood, and excessive fatigue even while at rest. Unexplained weight loss may also occur. If any of these symptoms present in a patient who has experienced high levels of exposure to asbestos, mesothelioma should be suspected and tested for.
Diagnosis of malignant pleural mesothelioma involves assessment of symptoms, followed by tests such as x-rays, MRI or CT scans, and biopsies. The cells collected during a biopsy will be examined under an electron microscope. More invasive techniques, such as a bronchoscopy or thoracoscopy, may be utilized as well. A bronchoscopy uses a lighted, flexible tube inserted into the patient's mouth and down the trachea to look for tumors, or to remove tissue for a biopsy. In thoracoscopy, a tube is inserted into the pleural space through a small incision and used to examine the chest and remove tissue samples.
Once a diagnosis of pleural mesothelioma has been made and confirmed, the cancer will be staged, and a treatment plan will be determined by the oncologist and the patient. Several factors determine the possible treatments, including the stage and extent of the cancer, the location and size of the cancer, the patient's overall health and strength, and the patient's wishes.
The average life expectancy for a pleural mesothelioma patient is only six to 18 months, depending on the stage of the cancer. There have been some notable patients who lived much longer, but the majority of those afflicted with mesothelioma have a grim prognosis, and are encouraged to put their affairs in order even as they are pursuing treatment.
If caught early enough, in Stage I, the cancer may be able to be surgically resected, or removed. A pleurectomy removes the pleura itself, along with the cancer, and may remove other tissues. An extrapleural pneumonectomy removes the entire lung and pleura. Sections of the lung may be removed individually, as well. This is not common, however, because few cases of mesothelioma are diagnosed this early; the diffuse nature of the tumor, which spreads like a rind across the lungs' covering, also makes surgery tricky.
Chemotherapy and radiation may be administered to patients deemed strong enough to endure their side effects. If at all possible, the patient will be given a combination of all three treatments. Often, however, curative treatment is not feasible, and the option of palliative treatment will be pursued.
Palliative treatment is meant to alleviate the symptoms, such as pain, breathing difficulty and discomfort, associated with malignant pleural mesothelioma. All three forms of treatment may be used in a palliative fashion. Some palliative surgical procedures include thoracentesis, which removes the excess pleural fluid that causes discomfort, and pleurodesis, a technique which helps prevent the fluid from accumulating in the first place.
Clinical trials may be an option for some patients, and this possibility should be discussed with the oncologist. These trials investigate such experimental treatments as photodynamic therapy, immunotherapy, and gene therapy, as well as new chemotherapy drugs and new combinations of established therapies.
Many mesothelioma patients also benefit from the use of holistic, or complementary, approaches such as massage therapy, nutritional supplements, acupuncture, hypnotherapy and transcutaneous electrical nerve stimulation. These therapies can be used on their own, or to augment the traditional therapies. They are also effectively used to counteract or provide relief from the side effects of chemotherapy and radiation therapy, most notable nausea and vomiting.