Mesothelioma

Mesothelioma is a rare form of cancer that is directly associated with prolonged exposure to asbestos. Although reported incidence rates of mesothelioma have increased in the past 20 years, it is still a relatively rare cancer. About 2,000 new cases of mesothelioma are diagnosed in the United States each year.

Mesothelioma cancer affects the mesothelium, a membrane that covers and protects most of the internal organs of the body. Because mesothelioma can take a long time to detect, from 10 to 50 years (or even more), diagnosing mesothelioma is often difficult. The majority of mesothelioma diagnosis occurs after the cancer is already in its advance stages. Consequently, most people diagnosed with mesothelioma usually pass away within two to four years.

The mesothelium has different names, depending on its location in the body. The membrane that surrounds the lungs and lines the wall of the chest cavity is called the pleura. Most cases of mesothelioma affect the pleura. Other cases of mesothelioma have been reported on the peritoneum (10-20% of all mesothelioma cases), the outer membrane that lines the abdominal cavity, and the pericardium (the rarest form of mesothelioma), the outer membrane that covers the heart.

Although science is not certain as to the exact mechanism that causes mesothelioma, the leading theory believes that the asbestos fibers puncture the parenchyma, become lodged in the mesothelium, and by process of irritation stimulate the changes in the cells which lead to mesothelioma.

Who is at Risk?

In almost all cases of mesothelioma, affected people have been exposed to asbestos for a prolonged period of time. That is why most mesothelioma cases involve individuals who have worked in asbestos mines, asbestos fabrication plants, and construction or home renovation involving the handling and installation of asbestos for insulation or asbestos cement products. A history of asbestos exposure at work is reported in about 70 percent to 80 percent of all mesothelioma cases. Family members of the individuals can be affected since they may be exposed to asbestos from washing the asbestos-laden clothes and hair of those individuals.

The risk of asbestos-related disease increases with heavier exposure to asbestos and longer exposure time. However, some individuals with only brief exposures have developed mesothelioma. The U.S. Occupational Safety and Health Administration (OSHA) have set limits for acceptable levels of asbestos exposure in the workplace today. People who work with asbestos wear personal protective equipment to lower their risk of exposure.

Occupations where you are at a higher risk to contract mesothelioma include:

• Brake Mechanics
• Steel Workers
• Insulators
• Boilermakers
• Shipfitters
• Maintenance Workers
• Pipe Fitters

Mesothelioma Historical Perspective

The dangers of asbestos became more evident during the early 20th century. In the 1930's, numerous medical journals published studies that linked asbestos to cancer. During this time, a seminary publication called "Pulmonary Asbestosis: Carcinoma of the Lung in Asbesto-Silicosis" was published in the American Journal of Cancer that suggested that asbestos was the primary cause of lung cancer in cases involving people with occupational exposure to asbestos. This was confirmed in 1955, when an unmistakable connection between the ingestion of asbestos fibers and the development of certain forms of lung cancer, what later came to be known as mesothelioma. Continuing the trend, the British Journal of Industrial Medicine published a paper, "Diffused Pleural Mesothelioma and Asbestos Exposure in the North Western Cape Province" in 1960 that definitively linked mesothelioma with exposure to crocidolite asbestos. The study examined over 30 cases of cancer in South African asbestos mine workers.

The evidence linking asbestos exposure to mesothelioma continued to mount. The most startling example occurred in the Western Australian town of Wittenoom. Wittenoom was home to an asbestos mine and mill. A medical study revealed the first diagnosed case of malignant mesothelioma in an Australian asbestos worker in the Medical Journal of Australia. The worker had worked in the mill at the asbestos mine in Wittenoom from 1948 to 1950. Further investigations revealed a high incidence of mesothelioma and other health ailments in not only people who worked directly in the mines, but also in people who didn't work in the mines, but lived in the town. It began to surface that the dust associated with asbestos mining and milling was affecting the town, contributing to the development of mesothelioma and other asbestos-related diseases. By 1978 the Western Australian Government decided to phase out the town of Wittenoom.

Symptons of Mesothelioma

Some of the earliest symptoms of mesothelioma are non-specific, and can often be mistaken for less serious illness (such as viral pneumonia) and are commonly overlooked. The majority of people affected with mesothelioma do not develop any symptoms of sickness during the early stages of cancer development. This is big reason why mesothelioma is seldom detected during its early stages. Symptoms of mesothelioma may not appear until 10 to 50 years after exposure to asbestos - depending on the dose and longevity of asbestos exposure.

The main symptoms of pleural mesothelioma are shortness of breath (dyspnea) and chest pains in the chest. The accumulation of fluid between the lining of the lung and the chest cavity, otherwise known as pleural effusion, is one of the most common symptoms of mesothelioma. It the accumulation of pleural effusion that manifests itself as shortness of breath and chest pains. Other symptoms such as lower back pains, fever, muscle weakness, sensory loss, persistent cough, coughing up blood, hoarseness of voice, and swelling of face and arms, have been reported in pleural mesothelioma.

Symptoms of peritoneal mesothelioma include weight loss, fatigue, nausea, abdominal pains, and abdominal bloating due to a buildup of fluid in the abdominal cavity. Other symptoms of peritoneal mesothelioma may include obstruction of the bowel, blood-clotting abnormalities, anemia, swelling of feet, and fever.

Symptoms of pericardium mesothelioma are obviously cardiovascular rated, and includes rhythmic disturbances such as palpitations, hyper- or hypo- tension, irregular heartbeat, fatigue, and loss of appetite.

A big danger of mesothelium, like any other cancer, is the chance that it may metastasize and affect other organs. If the cancer has spread beyond the mesothelium to other parts of the body, symptoms may include pain, trouble swallowing, or swelling of the neck or face.

Diagnosis of Mesothelioma

Early diagnosis of mesothelioma is often difficult, because the symptoms are similar to those of a number of other conditions. This is the reason why most diagnosis occurs in the advance mesothelioma only.

However, whenever these non-specific symptoms present themselves, people should see a doctor, particularly if they are occupationally exposed to asbestos.

Diagnosis begins with a review of the patient's medical history, most importantly determining any history of asbestos exposure. A complete physical examination may be performed, including x-rays of the chest or abdomen and lung function tests. A CAT scan or an MRI may be taken to further visualize the area.

A diagnostic thoracentesis, in which cells are extracted from the pleural cavity is many times used as an aid in the diagnosis of mesothelioma. However, this test is not usually considered reliable since in up to 85% of the cases, the fluid tests negative or inconclusive even though cancer is present. For a more thorough diagnosis, a needle biopsy of the pleura or an open surgical tissue biopsy is necessary to confirm the existence of mesothelioma. In a biopsy, a surgeon or a medical oncologist removes a sample of tissue for examination of cancerous cells.

If the diagnosis is confirmed to be mesothelioma, the next medical step is to determine the extent of the cancer, or the stage of cancer development. Like any other cancer, it is important to find out whether your cancer is benign or malignant. And if it is malignant, it is important to find out whether the cancer has spread to other parts of the body. And if so, which parts.

Mesothelioma is described as localized if the cancer is found only on the membrane surface where it originated. Mesothelioma is classified as advanced if it has spread beyond the original membrane surface to other parts of the body, such as the lymph nodes, lungs, chest wall, or abdominal organs. The use of x-rays, CAT-scans, and MRIs are useful in determining the extent of the cancer.

Mesothelioma Treatment

 

Earlier diagnosis of mesothelioma is critical for more effective treatment.  Prognosis in this disease is consistently difficult to evaluate since there is great variability in the time before diagnosis and the rate of disease progression, which is what makes malignant mesothelioma an extremely dangerous cancer.  It is estimated that three to five people die each day in the United States because of mesothelioma.  Unfortunately, mesothelioma is a cancer which most medical, surgical and radiation oncologists have little or no experience in treating due to its rarity.  If the cancer is detected in its advanced stages, current treatments have been relatively ineffective.

The chance of recovery for a person with mesothelioma depends on several factors, including:

• Size of the cancer
• Location of the cancer
• Spread of the cancer throughout the body
• Response to treatment
• Appearance of the cells under a microscope (histology)
• Age of the patient

Currently, there are three traditional methods of fighting cancerous mesothelioma.  These are surgery, chemotherapy drugs, and radiation therapy.

Surgery

Surgery for malignant mesothelioma can be aimed at long-term control (aggressive surgery) or relief of symptoms (palliative procedures).  Surgery is by no means a cure against the disease rather it is used to hopefully prolong survival.  Considerations for surgery for malignant mesothelioma, requires a thorough evaluation of the patient's overall health.  Tests are performed to make sure the patient that the cancer has not metastasize to spread to other organs; and to evaluate the overall performance of the patient's lung and heart functions.

Aggressive Surgery – The most common aggressive surgery procedure is an extrapleural pneumonectomy, which is the removal of the pleura, the lung, the diaphragm and the pericardium.  The objective of this very complicated and aggressive surgical procedure is to remove as much of the tumor on the mesothelium as possible.  Because of the highly specialized nature of this surgery and because it carries a high risk of death within 30 days of the surgery, not all hospitals can perform this procedure.  Patients are carefully evaluated to determine their ability to tolerate the surgery, thus extrapleural pneumonectomy is generally performed only in younger patients in good overall health with the cancer in its early stages (Stage I).       

Palliative Surgery – These surgical procedures are performed to relieve and/or control symptoms associated with advanced malignant mesothelioma.  Lung function often is reduced in these patients for several reasons; the biggest being pleural effusion (fluid collection) and the tumor mass can compress the lung.  This can lead to symptoms such as breathlessness and chest pains. 

Thoracentesis is commonly performed to treat effusion in pleural mesothelioma.  This surgery involves inserting a needle into the chest to drain the excess fluid, relieving breathlessness and chest pain.  Talc may be introduced into the pleura to limit recurrence of the effusion.  Pleurectomy is the surgical removal of the pleura. This procedure is performed to reduce pain caused by the tumor mass, or to prevent the recurrence of pleural effusion.  For peritoneal mesothelioma, surgery generally is aimed at relieving symptoms, such as recurrent ascites or bowel obstruction.  As with pleural mesothelioma, complete surgical removal of the entire tumor is unlikely.

Chemotherapy (Mesothelioma Drugs)

Chemotherapy is the use of medications to treat cancer.  In regards to the treatment of malignant mesothelioma, chemotherapy has had mixed results.  Chemotherapy is usually administered after surgery in an attempt to kill cancer cells that could not be removed during the surgical procedure.  Drugs that are currently used to treat mesothelioma include Adriamycin, Taxol, Altima, Oconase, and Gemcitabine.  A strategy to improve the efficacy of chemotherapeutic treatment is combination chemotherapy.  This is using more than one drug at the same time.  Some combinations have shown some promise in treating mesothelioma.  Currently new drugs are being developed with some of these drugs entering the latter stages of clinical trials evaluations.

Radiation Therapy

Radiation therapy on its own is generally not effective because of the location of malignant mesothelioma.  It is extremely difficult to deliver sufficiently high doses of radiation to kill the tumor on the mesothelium without damaging the surrounding organs.  Although radiation therapy after surgery has not been shown to improve survival, lower doses of radiation can result in some reduction in the disease, but it is unclear whether this reduction actually results in longer survival than no treatment.  That is why radiation therapy is often used after surgery has been performed.  Radiation therapy, in these cases, is meant to kill any remaining tumor cells that may be remaining after surgery.  In addition, radiation therapy can be used to relieve symptoms of mesothelioma, including chest pain.