Pleural Mesothelioma

There are various forms of mesothelioma that result from inhalation of asbestos fibers; however, the most common type of the disease is pleural mesothelioma. This type of cancer is present in the chest cavity where cancer cells attack tissues of the chest and lungs. Approximately 75 percent of the 2,000 newly diagnosed cases of mesothelioma per year are related to the membranes that line the chest cavity and lungs, also referred to as pleura.

Pleural cancer is a serious condition that affects the pleural lining of the chest wall and lungs. This lining protects the lungs and consists of two separate layers; the parietal pleura lines the interior chest wall, while the visceral pleura surrounds the lungs directly and offers added protection to these vital physical systems. Both layers of the pleura are lubricated by fluids produced by the lymph nodes. Pleural cancer attacks both of these layers directly and can also cause a buildup of fluid between them, creating serious side effects and symptoms for patients suffering from this illness.

Types of pleural cancer

Pleural mesothelioma is the most common form of pleural cancer and is often attributable to prolonged or frequent exposure to asbestos. Generally regarded as incurable, malignant pleural mesothelioma first manifests itself in the form of tumors on and in the parietal pleural layer and from there spreads to the visceral layer, forming large, fast growing tumors that can significantly affect breathing and comfort for patients. Other pleural cancers are usually metastatic in nature, meaning that the cancer has spread from another area of the body to the pleura. Breast cancer and lung cancer are most often the originating sources for these metastatic pleural cancers.

Causes of pleural cancer

By far the most common cause for pleural cancer is asbestos exposure. A link between asbestos and pleural mesothelioma was first identified in 1960; since that time, strict regulations on asbestos in the workplace have been instituted in the U.S., but developing countries still allow its use in a number of commercial and industrial processes. Because asbestos-related pleural mesothelioma can take decades to manifest itself in patients, the global effects of asbestos exposure may continue to impact the working population in these developing economies for years to come. Other factors that may play a role in causing pleural mesothelioma include exposure to radiation as well as certain genetic factors that could predispose patients to this serious form of cancer.

Prognosis for Pleural Mesothelioma

The prognosis for patients with pleural mesothelioma is dependent on what stage the disease is in when it is discovered and how it is treated. If the disease is diagnosed when it is in a late stage, which is not uncommon, patients likely die within one year of their diagnosis.

Staging

Advances in understanding and treatment are complicated by the fact that the disease is rare, thus few patients suffering from it are seen at any one institution. Another factor is the use of non-uniform and inaccurate staging systems over the past four decades, leading to unnecessary confusion about progression and outcome, and an inability to accurately predict survival rates - a problem the universal use of the TNM system is aimed to correct.

As associations like the International Mesothelioma Interest Group knit together specialists in pulmonary medicine, thoracic surgery, medical oncology, radiation therapy, epidemiologists, pathologists and researchers into a single tool aimed at solving the ongoing challenges of malignant pleural mesothelioma in both its early and latter stages, TNM will become an increasingly valuable weapon, providing a "universal language" for talking about the disease.
The Ninth Annual Meeting of the International Mesothelioma Interest Group, held in Amsterdam in September of 2008, brought little resolution and no new medicines beyond cisplatin, gemcitabine and pemetrexed - which are still the most common forms of chemotherapy.

In addition, most cancer treatment centers continue with a multimodal regimen that also includes radical surgery and postoperative, high-dose radiation treatments among patients who remain at Stage 3.

The next meeting of the International Mesothelioma Interest Group, scheduled for 2010, may bring some resolution for those unfortunates categorized in Stage 4 of TNM. If not, a recently emerged diagnostic tool, pleural fluid testing (which takes fluid from the pleural effusions commonly seen in pleural mesothelioma), has shown an almost 100-percent specific association between mesothelin levels and mesothelioma, even in early-stage cancers.

The common elements of any staging system generally include the location of the primary, or initial tumor; the size of the tumor; the number of tumors; the involvement of lymph nodes, which predict metastasis; the types of cells found in the tumor (whether like heart cells, liver cells or the like); how much these cells deviate from normal cells; and the presence of metastases.