Pleural Mesothelioma

Pleural Mesothelioma

Malignant mesothelioma is a rare form of cancer that can develop in people who are repeatedly exposed to asbestos. Two to three thousand Americans are diagnosed with this type of cancer each year, and of those, around two thirds have the pleural form of mesothelioma.
Pleural mesothelioma develops in the lining of the lungs. This lining is called the pleura, or pleural membrane, and it is made up of mesothelial cells. This pleural membrane consists of two layers - the parietal layer, and the visceral layer. The parietal layer is an outer layer that lines the entire chest cavity and diaphragm, while the visceral layer is an inner layer that covers the lungs. Together, these two layers provide support and protection for the lungs and the chest cavity.

How does Asbestos cause Pleural Mesothelioma

The method by which asbestos causes pleural mesothelioma is much better understood than for other types of mesothelioma. In cases of pleural mesothelioma, asbestos exposure occurs via inhalation of asbestos fibers. Once these fibers have entered the lungs, they work their way to the pleural membrane, and the body is not able to expel them. Over a long period of time - typically two decades or more - asbestos fibers cause changes in these pleural cells, which may cause scarring of the lungs and, eventually, the formation of tumors.
When pleural cells become cancerous, they are no longer regulated by the mechanisms that control division of normal healthy cells. They begin to divide continuously, and this causes thickening of pleural membranes. As a result, lung capacity is reduced, and fluid begins to build up between pleural layers.

Symptoms

Thickening of pleural membrane layers and the resulting build-up of fluid (called pleural effusion) begins to put pressure on the lungs and the respiratory system in general, preventing normal breathing. Symptoms of pleural mesothelioma are largely caused by these developments, and may include the following:

• Persistent dry or raspy cough
• Coughing up blood
• Difficulty in swallowing
• Shortness of breath that occurs even when at rest
• Persistent pain in the chest or rib area, or painful breathing
• Development of lumps under the skin on the chest
• Night sweats or fever
• Unexplained weight loss
• Fatigue
  

Diagnosis

As with other types of mesothelioma, pleural mesothelioma is difficult to diagnose. There are two reasons for this. First, the long latency period of the disease means that often, cancer develops long before the first symptoms are noted. Second, the symptoms of pleural mesothelioma are very non-specific. In the early stages, pleural mesothelioma symptoms are often mistaken for those of less threatening diseases such as influenza and pneumonia.
Diagnosis of pleural mesothelioma is made partly on the basis of symptoms, but because symptoms are non-specific, additional diagnostic tested are needed to confirm the presence of cancer. Following a medical history and physical examination, patients must typically undergo imaging tests to confirm the location of cancer, and fluid and tissue tests to confirm the type of cancer involved.

Treatment

All forms of mesothelioma are very aggressive and often resistant to treatment. In addition, early diagnosis is so rare that mesothelioma treatment is usually not able to provide a complete cure.
However, with the development of new drugs and early detection techniques, the outlook is improving for pleural mesothelioma patients in particular, because this is the most common form of mesothelioma and there is a much larger body of knowledge and research to draw upon in treating patients. According to some current studies, about 10% of all pleural mesothelioma patients will survive for three to five years following diagnosis, and about 5% will survive five years or more.
In general, pleural mesothelioma patients have three options: surgery, chemotherapy, and radiation therapy. Typically, patients will receive a combination of two or more of these types of treatment.
Early detection of pleural mesothelioma can improve a patient's prognosis considerably, and such patients have more extensive treatment options. If the disease is diagnosed early enough, surgery to remove localized tumors, followed by chemotherapy or radiation therapy to kill any remaining cancer cells, can be an effective treatment. Curative surgery candidates must be in a good general state of health, and their cancer must not have spread beyond localized sections of the lungs.
Pleural mesothelioma patients who are not diagnosed early enough for curative treatment have fewer treatment options, and these are mostly limited to palliative treatments. These types of treatments are designed to relive pain and discomfort to improve a patient's quality of life, rather than to improve their prognosis. Palliative treatments include removal of built-up fluid from the pleural spaces, and surgical removal of tumors, to relieve pressure on the lungs.