What is Mesothelioma?
Throughout the past decade, the term "mesothelioma" has become more and more recognizable. Once an obscure disease that meant little to the general public, mention of this disease now conjures up thoughts and pictures of factories and mines strewn with asbestos and the unfortunate workers who were employed in those dangerous places.
Thanks to concerned medical professionals, researchers, and watchdog organizations, we're learning more and more about mesothelioma and how it affects the lives of those who are afflicted. However, there's still far to go as both better treatments and a cure for the disease are sought.
About the Disease
Simply put, mesothelioma which is commonly referred to as asbestos cancer, is an aggressive cancer caused primarily by the inhalation of dangerous asbestos fibers. The disease attacks the mesothelium, a protective, two-layered membrane that covers the internal organs of the body including the lungs, heart and abdominal organs. Between these layers, the cells produce fluid, which allows easy movement of the heart and lungs within the chest cavity. The layer that covers the lungs is called the pleura, and the layer that covers the heart is called the pericardium. The peritoneum lines the abdominal cavity. Mesothelium also lines the male and female reproductive organs. Mesothelioma can affect any of these cells, but is usually seen in the pleural or peritoneal mesothelium. The most commonly diagnosed form of this cancer is pleural mesothelioma.
Mesothelioma takes anywhere from 20 to 50 years to develop, which is why older individuals are usually the victims. However, recent cases involving September 11th World Trade Center first responders and clean-up crews show that high concentrations of asbestos can cause the disease to develop much more rapidly. A few WTC workers have already died of the disease.
Effects of the Disease
The invasion of the mesothelium by cancer cells makes it very difficult for the patient to breathe, resulting in the need for oxygen, especially as the disease progresses. Those with the pleural form of mesothelioma may also suffer from pleural effusions. These effusions prevent the smooth movement of the lungs and other organs in the chest. Peritoneal mesothelioma also affects the stomach area and abdominal cavity, causing nausea, vomiting, or loss of appetite, which can result in dangerous weight loss. In addition to breathing difficulties and loss of appetite, mesothelioma victims also complain of excessive coughing, sleeping difficulties, persistent chest pain, fever, and pain in the lower back.
Mesothelioma, in general, is a very painful disease and because it is usually not diagnosed until it's in an advanced stage. For this reason, the symptoms are typically quite serious. Late diagnosis also means that the cancer is more likely to have metastasized, or spread, making successful mesothelioma treatment even more difficult.
Who Gets Mesothelioma?
Statistics show that, because of their work history, the disease most often affects men between the ages of 50 and 70 who were employed in an asbestos-laden environment before asbestos warnings and bans were in place in the 1970s. Though women still have a much lower frequency of the disease, cases of second-hand exposure to asbestos has prompted more diagnoses among women, especially those whose male family members worked with asbestos. The occupations most associated with mesothelioma are shipyard workers, electricians, plumbers, construction industry workers, pipefitters, boilermakers, and anyone subject to heavy exposure to dangerous asbestos and airborne asbestos fibers.
An abundance of cases have also demonstrated that mesothelioma can develop among people who lived in communities where asbestos factories or mines were located. In some instances, entire towns have been adversely affected by the presence of asbestos fibers in the air. For example, in Libby, Montana - site of a former vermiculite asbestos mine - hundreds have already died of mesothelioma.
Though still significantly rarer than other cancers, an estimated 2,000 to 3,000 new cases of mesothelioma are diagnosed each year in the United States. Other countries, notably the United Kingdom and Australia, report a much higher incidence of the disease. Nevertheless, the United States - like many other countries - has seen an increase in asbestos-caused cancer as men who worked in U.S. shipyards in the 1940s and 1950s, at the height of production, are now being diagnosed with mesothelioma.
Dealing with Mesothelioma
Mesothelioma is most often diagnosed in its late stages, and such a diagnosis is devastating to the individual and his/her family. Though research into the disease has been ongoing, there is currently no cure for mesothelioma. Some patients may be candidates for surgery to remove tumors or even an entire lung, but most are better treated with radiation or chemotherapy. More often than not, these treatments are palliative, serving to lessen the severity of the symptoms of the disease rather than offering a cure.
Medical professionals and research scientists, however, are constantly exploring new ways to combat the disease. For example, doctors know that some combinations of chemotherapy drugs work better than others and tests developed to ascertain earlier diagnosis of the disease or to monitor those most at risk have arrived on the scene.
Who's to Blame?
The reason someone develops mesothelioma is usually the lack of proper protection offered to those who worked with asbestos. Though the dangerous properties of asbestos and asbestos products have been evident for decades, many employers neglected to protect their workers from inhaling asbestos while on the job. It wasn't until public awareness of the dangers of the material were revealed in the 1970s that many employers began offering protective clothing such as respirators, gloves, aprons, and other such items to those working with asbestos on a daily basis.
Due to the negligence of employers, many companies who manufacture asbestos or products that contain asbestos have been subject to literally thousands of lawsuits filed by those who've been harmed by the material. Many of those lawsuits have come from individuals suffering from mesothelioma.
* Dodson, R. and Hammar, S. Asbestos: Risk Assessment, Epidemiology, and Health Effects. Taylor & Francis: Boca Raton. 2006.
* Stahel RA,Weder W, Felip E; ESMO Guidelines Working Group. Malignant pleural mesothelioma: ESMO clinical recommendations for diagnosis, treatment and follow-up. Clinic and Policlinic of Oncology, University Hospital of Zurich, Switzerland. 2008.
* Pass, I., Vogelzang, N., Carbone, M. Malignant Mesothelioma: Advances in Pathogenesis, Diagnosis, and Transitional Therapies. Springer: New York. 2005.
* http://www.cancer.gov/cancertopics/types/malignantmesothelioma (http://www.cancer.gov/cancertopics/types/malignantmesothelioma)
* http://www.nlm.nih.gov/medlineplus/mesothelioma.html (http://www.nlm.nih.gov/medlineplus/mesothelioma.html)
Last modified: December 18 2008.
What is mesothelioma?
Malignant mesothelioma is the most serious of all asbestos-related diseases. Although uncommon, mesothelioma is no longer considered rare. Mesothelioma is a cancer that is particulary difficult for doctors to diagnose and one that does not respond well to therapy.
The chest cavity, abdominal cavity, and the cavity around the heart are surrounded by a a layer of specialized mesothelial cells. Most other internal organs are also covered by these cells. The tissue formed by these cells is called mesothelium.
A special protective lubricating fluid that allows organs to move around is produced by the mesothelium. This protective fluid helps the lungs to move without resistance inside the chest cavity while breathing. The medical name for the mesothelium of the chest is the pleura and the medical name for the mesothelium of the abdomen is the peritoneum. The mesothelium of the "sac-like" space around the heart is called the pericardium.
A malignant (cancerous) tumor of the mesothelium is called a malignant mesothelioma. As most mesothelial tumors are cancerous, malignant mesothelioma is often simply called mesothelioma. Tumors of the mesothelium can also be benign (noncancerous) but benign mesotheliomas are much more rare.
Mesothelioma was recognized as a tumor of the pleura, peritoneum and pericardium in the late 1700's. However it was not until much later, in 1960, that this particular type of tumor was described in more detail and even more importantly, its association with asbestos exposure was recognized. The first report linking mesothelioma to asbestos exposure was written by J.C.Wagner, and described 32 cases of workers in the "Asbestos Hills" in South Africa. Since than the relationship between mesothelioma and asbestos exposure has been confirmed in studies around the world.
The incidence of mesothelioma in the United States remains very low, with 14 cases occurring per million people per year. Despite these numbers the noticed threefold increase in mesothelioma in males between 1970 and 1984, is directly associated with environmental and occupational exposure to asbestos, mostly in areas of asbestos product plants and shipbuilding facilities.
Although the disease is much more commonly seen in 60-year old men, it has been described in women and early childhood as well. The cause of the disease is not so well understood in these latter two groups, but there is some evidence of possible asbestos exposure for some of these cases as well.
Malignant mesotheliomas are divided into three main types. About 50% to 70% of mesotheliomas are the epithelioid type. This type has the best prognosis (outlook for survival). The other two types are the sarcomatoid type (7%-20%), and the mixed/biphasic type (20%-35%). Treatment options for all three types are the same.
About three-fourths of mesotheliomas start in the chest cavity. They are known as pleural mesothelioma. Another 10% to 20% begin in the abdomen. These are called peritoneal mesothelioma. Pericardial mesothelioma, starts in the cavity around the heart, and is very rare. The covering layer of the testicles is actually an outpouching of peritoneum into the scrotum. Mesotheliomas that affect this covering of the testicles are quite rare.
* What mesothelioma information is currently available?
* What are the different types of mesothelioma?
* What are the risk factors for mesothelioma?
* What causes mesothelioma?
* What are the signs and symptoms of mesothelioma?
* How is mesothelioma diagnosed?
* How is mesothelioma staged?
* What treatments are available for mesothelioma?
Glossary of Terms
asbestos: combination of several minerals that separate into long, threadlike fibers. Because they do not burn, do not conduct heat or electricity, and are very resistant to chemicals, these minerals are often used for making fireproof materials, electrical insulation, roofing, filters, etc. benign: doing no harm, good incidence: the frequency with which an event occurs (usually in a group at risk) pericardium: a thin membrane surrounding the heart and the roots of the great blood vessels.
peritoneum: a thin membrane that covers the abdominal cavity and partially covers some of the abdominal organs.
pleura: a thin membrane that covers the lungs (visceral pleura) and lines the chest cavity (parietal pleura) malignant: harmful, dangerous (a malignant tumor is a cancer).
median: middle number in a series of numbers (for example: median survival of 10 months means that for that specific group of patients the survival varied from probably 2 months to 30 months).
mesoderm: the middle layer of cells in an embryo, from which the muscular, skeletal, vascular, connective etc. tissues develop.
mesothelioma: a tumor of the mesothelium, that can be benign (localized) or malignant (diffusely spread), and that is most commonly caused by the ingestion of asbestos particles.
mesothelium: the thin layer of mesodermal epithelial cells that forms the pleura, peritoneum, pericardium.
metastases: the spread of tumor cells from one part of the body to another unrelated part of the body by the way of the bloodstream or lymphatics.
prognosis: prediction of the probable course of the disease in an individual. Prognostic factors are factors associated with prognosis.
TNM staging: assigning a stage to the tumor based on size, local versus disseminated growth, lymph node involvement and presence or absence of distant metastases.
tumor: a mass of tissue, a growth independent of its surrounding structures and having no physiological function/ a neoplasm. A tumor can be benign or malignant.