What is Mesothelioma
Mesothelioma is a rare cancerous disease of the mesothelium, which is a type of protective tissue that surrounds organs found in the thoracic and abdominal cavity such as the lungs, heart, liver, and abdominal organs mainly the lung. Most of the time, cancer does not occur with a single cause; rather it is a group of diseases with multiple causes, symptoms, treatments, and prognosis. But in the unique case of mesothelioma, there is a specific cause for this cancerwhich is asbestos
:Risk Factors
asbestos is still the leading cause of mesothelioma
Virus
In very rare case, the (SV40) virus may act as a carcinogen and potentiate asbestos in causing malignant mesothelioma. The SV40 is a highly controversial virus due to the contamination of polio vaccines between the year 1955 and 1963. Millions of people in the United States were said to be exposed to the virus.
However, there is no clear evidence yet whether SV40 is responsible for certain mesotheliomas.
In very rare case, the (SV40) virus may act as a carcinogen and potentiate asbestos in causing malignant mesothelioma. The SV40 is a highly controversial virus due to the contamination of polio vaccines between the year 1955 and 1963. Millions of people in the United States were said to be exposed to the virus.
However, there is no clear evidence yet whether SV40 is responsible for certain mesotheliomas.
Erionite Zeolite
Exposure to erionate, a type of zeolite mineral that has similar properties with asbestos, is suggested to be one of the causes of mesothelioma in Turkey.
Radiation
Therapeutic radiation using thorium oxide was reported to increase the risk of developing pleural and peritoneal mesothelioma in certain people.
Smoking
Smoking alone is not considered to affect the development of mesothelioma, however, when smoking is combined with asbestos exposure, the risk of having mesothelioma significantly increases.
Asbestos
For several decades, asbestos remains the primary cause of the development of mesothelioma and a number of lung diseases. Inhalation of the particles is the most common route of entry, which is why most cases of mesothelioma occur in people working in the asbestos industry.
what is Asbestos
Asbestos is the given name of a certain family of minerals that occur in fibrous form. These fibers can be processed into a variety of materials that are uniquely resistant to fire, heat, and corrosion. Asbestos can be spun and woven into textiles, matted into insulating materials, or used with other substances to make numerous products, including brake linings, clutch pads, and roofing and flooring materials. Because of these, asbestos is almost irreplaceable as no other substance provides its desirable properties.
Nevertheless, manufacturers are developing replacement materials because of the issues surrounding the production of asbestos products. Inhalation of asbestos’ very minute fibers over a period as little as one to two months has been linked to cancers of the lung, lung-cavity lining or mesothelioma, asbestosis, and severe lung impairment.
Types of Asbestos
There are two general varieties of asbestos: serpentine and amphibole.
Serpentine
Chrysotile, obtained from serpentine rocks, is the most abundant and widely used form of asbestos accounting for 90% of asbestos used for production of new materials.
Amphibole
Amphiboles are long, thin fibers that are more potent in causing lung cancer and associated diseases. Amphiboles include amosite (brown asbestos), crocidolite (blue asbestos), tremolite, actinolite, and anthophyllite. Among these, crocidolite is the more potent carcinogen which is due to its rod-like appearance that enables the fiber to easily penetrate the lungs and into the pleura. They may cause irritation and long-term inflammation of the mesothelium altering cellular structures leading to cancer. Asbestos can also cause the production of free radicals that damage cells that further potentiate cancer growth. It has been suggested that some of the fibers may be coughed up and swallowed into the gastrointestinal tract. In this way, asbestos can cause peritoneal (abdominal) mesothelioma.
People who are working with asbestos have the highest risk of contracting mesothelioma. But family members of these workers may also incur the disease due to particles that may be carried along with the worker’s clothing and hair. Aside from that, those who are residing in a room with products built from asbestos are likely to inhale the particles without knowing it. Houses and structure built in the late 1800s to mid 1900s are more prone to use such materials because asbestos has been widely used commercially during this period. The latency period of mesothelioma can last between 20 to 50 years following exposure to asbestos.
Diagnosis
Diagnosing mesothelioma is often difficult, because the symptoms are similar to those of a number of other conditions. Diagnosis begins with a review of the patient's medical history. A history of exposure to asbestos may increase clinical suspicion for mesothelioma. A physical examination is performed, followed by chest X-ray and often lung function tests. The X-ray may reveal pleural thickening commonly seen after asbestos exposure and increases suspicion of mesothelioma. A CT (or CAT) scan or an MRI is usually performed. If a large amount of fluid is present, abnormal cells may be detected by cytopathology if this fluid is aspirated with a syringe. For pleural fluid, this is done by thoracentesis or tube thoracostomy (chest tube); for ascites, with paracentesis or ascitic drain; and for pericardial effusion with pericardiocentesis. While absence of malignant cells on cytology does not completely exclude mesothelioma, it makes it much more unlikely, especially if an alternative diagnosis can be made (e.g. tuberculosis, heart failure). Unfortunately, the diagnosis of malignant mesothelioma by cytology alone is difficult, even with expert pathologists.
Generally, a biopsy is needed to confirm a diagnosis of malignant mesothelioma. A doctor removes a sample of tissue for examination under a microscope by a pathologist. A biopsy may be done in different ways, depending on where the abnormal area is located. If the cancer is in the chest, the doctor may perform a thoracoscopy. In this procedure, the doctor makes a small cut through the chest wall and puts a thin, lighted tube called a thoracoscope into the chest between two ribs. Thoracoscopy allows the doctor to look inside the chest and obtain tissue samples. Alternatively, the chest surgeon might directly open the chest (thoracotomy). If the cancer is in the abdomen, the doctor may perform a laparoscopy. To obtain tissue for examination, the doctor makes a small incision in the abdomen and inserts a special instrument into the abdominal cavity. If these procedures do not yield enough tissue, more extensive diagnostic surgery may be necessary.
Immunohistochemical studies play an important role for the pathologist in differentiating malignant mesothelioma from neoplastic mimics. There are numerous tests and panels available. No single test is perfect for distinguishing mesothelioma from carcinoma or even benign versus malignant.
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