Symptoms
Diagnosis

Mesothelioma – The Disease

The National Cancer Institute defines mesothelioma as a rare form of cancer in which (malignant) cells are found in the sac lining of the chest (the pleura), the lining of the abdominal cavity (the peritoneum) or the lining around the heart (the pericardium). The mesothelium is a membrane that covers and protects most of the internal organs of the body and is made up of a layer surrounding the organ and another that forms a sac around it. The mesothelium produces a lubricating fluid between these layers that enables moving organs (such as the beating heart the expansion and contraction of the lungs) to move smoothly against adjacent structures.

Cancerous cells can invade and damage nearby tissues and organs, and may also metastasize (spread) from their original site to other parts of the body.

Asbestos and Mesothelioma

Asbestos is a naturally occurring group of minerals composed of fibers that can be separated into threads and woven. These fibers are strong, flexible and resistant to heat and chemicals. When bonded to other materials, asbestos fibers give products strength and stability. These characteristics have made asbestos popular in industry since the late 1800s, and an estimated 5,000 asbestos-containing products exist today.

There are two families of asbestos which differ based on the structure of their mineral crystals. Viewed under a microscope, the Amphibole family of asbestos has chainlike crystals, while the Serpentine family has layered sheets of fiber. The commercial industry uses four types of asbestos:

• Chrysotile, or white asbestos, accounts for almost 99% of asbestos used in the U.S. Chrysotile is in the serpentine family and has been linked to all asbestos-related illness;
• Crocidolite fibers are blue and are in the amphibole family;
• Amosite is in the amphibole family and has brown fibers;
• Anthophyllite, also an amphibole type asbestos has gray fibers

While asbestos fibers are extremely durable, when the fiber masses are disturbed they break apart and form a dust. The dust contains tiny fiber particles that become airborne and remain there for some time. Once asbestos settles, it can easily be disturbed and redistributed through a process known as reentrainment.

Airborne asbestos fibers can also be inhaled or swallowed. Once they enter the body, the fibers become lodged in tissues where they may remain latent (inactive) for up to 50 years. In the 1920s, asbestos fibers were linked to cancer and lung-related illness. By 1975 most of its uses were banned by the federal government and by 1989, the Environmental Protection Agency (EPA) had banned all new uses of asbestos. However, uses established prior to 1989 are still allowed. Today, asbestos use is tightly regulated and has dropped from the 719,000 cubic tons used in 1973 to 15,000 metric tons consumed in 1979. Still, there are an almost 733,000 buildings that were erected prior to the asbestos ban. Today, as many as 8 million people in the U.S. have already been exposed to asbestos and it continues to pose a serious threat to workers in certain occupations.

The building and construction industries use asbestos for strengthening cement and plastics. It is also used for insulation, fireproofing and sound proofing. Shipbuilders have used asbestos to insulate boilers, steam pipes and hot water pipes. Asbestos is used by the automotive industry in clutch pads and brake shoes. Other asbestos containing products include:

• Asbestos paper containing products such as heat and electrical wire insulation, industrial filters, table pads and sheet underlying flooring,
• Asbestos textile products like roofing materials, heat and fire-resistant fabrics including blankets and curtains,
• Ceiling and floor tile, paints, caulking and patching tape, coatings and adhesives, packing components, plastics.

While low-levels of exposure to asbestos are unlikely to cause significant health problems, workers who are exposed to asbestos through continuous contact with the fibers in their jobs face a very high risk of developing illness. Known as occupational exposure, the asbestos hazards are especially high in textiles, asbestos mining and milling, construction and building, demolition workers, drywall removers, auto workers (brake repair), ship builders, and power plants, oil and gas refineries, railroads, steel mills, people who reside near former asbestos manufacturing plants, Navy veterans, Merchant Marines, and Longshoremen. Families of workers are also susceptible to asbestos exposure through fibers that cling to industrial and trade worker’s clothes, shoes, skin and hair. This “second hand” exposure is known as paraoccupational exposure.

Once inhaled or swallowed, asbestos fibers travel to the lung where they become lodged in the pleura (the thin, saran-wrap type membrane lining the lungs). Scarring develops in the lungs and results in asbestosis, lung cancer and mesothelioma. Mesothelioma is a malignant tumor that aggressively invades the linings of the lungs, abdomen, heart or testicles. The two types of disease are pleural mesothelioma and peritoneal mesothelioma. Pleural mesothelioma spreads within the chest cavity and the metastases can occur in any organ, including the lungs and brain. Peritoneal mesothelioma penetrates the abdominal cavity and affects the liver, spleen or the bowel.

Every year, 2,500 to 4,000 patients are diagnosed with mesothelioma. One study of asbestos insulation workers reported a mesothelioma death rate up to 344 times higher than the general population.

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Symptoms
A mesothelioma diagnosis may be delayed because symptoms are generally non-specific and some patients do not even experience symptoms. The early symptoms of pleural mesothelioma may resemble viral pneumonia with a persistent cough and pain in the chest area. As the disease progresses, the accumulation of fluid (pleural effusion) in the chest cavity causes pain and is accompanied by difficult breathing and shortness of breath. Other pleural mesothelioma symptoms may include fever, loss, abdominal pain and swelling, bowel obstruction, night sweats, weight loss, blood clotting problems and anemia. Pain, difficulty swallowing and swelling of the neck or face may indicate that the cancer has metastasized beyond the mesothelium. Peritoneal mesothelioma symptoms may include the above, as well as swelling or abdominal pain due to a fluid build-up.

As the disease progresses, the cancerous cells harden the lung area and spread. As time passes, breathing, sleeping and eating become more difficult, and it becomes increasingly more challenging for the mesothelioma patient to engage in normal activities and enjoy life.

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Diagnosis
Doctors use a variety of diagnostic procedures to determine if a patient has mesothelioma. These exams may include:

• imaging tests,
• visualization tests,
• pathological tests,
• biopsies, and
• pulmonary function tests.

Because of the difficulties in diagnosing mesothelioma, doctors may perform other tests to confirm the presence of the disease. If the pathologist confirms a diagnosis of Mesothelioma, the doctor may request tests such as a Positron Emission Tomography (PET) scan to evaluate the stage or extent of the disease to decide an appropriate course of treatment.

To establish risk factors and the presence of symptoms, your physician will complete a medical history that includes questions to help determine the timeframe and environment in which you may have been exposed to asbestos. A physical exam will be performed that focuses on confirming the signs of mesothelioma and other health problems. Doctors will look for pleural mesotheliomas (tumors of the chest) since these patients often have fluid in their chest cavity caused by the cancer. Victims of peritoneal mesothelioma may have fluid in their abdominal cavity and pericardial effusion (fluid in the pericardium, or sac around the heart) which can also be discovered upon a thorough physical exam.

Imaging Techniques

Imaging techniques include computed tomography (CT) scans, in which a rotating x-ray beam is used to take a series of pictures of the body from different angles. A computer combines the series of pictures to produce a detailed cross-sectional image of a specific part of the body. To further enhance CT scan details, patients may be asked to have a harmless dye injected into their vein. Magnetic resonance imaging (MRI) scans are another imaging process which uses magnetic fields rather than x-rays to create images of specific areas of the body. CTs and MRIs help to pinpoint the location, size, and extent of the cancer.

Pathological Tests
A complement to radiological testing is removing fluid and tissue samples from the patient for further study. Many of these tests are performed in the hospital under local anesthetic.

A tissue sample of a pleural or pericardial tumor can be obtained using a relatively new technique called thoracoscopy. A thoracoscope (telescope-like instrument connected to a video camera) is inserted through a small incision into the chest. The doctor can see the tumor through the thoracoscope and can use special forceps to take a tissue biopsy. A laparoscopy can be used to see and obtain a biopsy of a peritoneal tumor. In this procedure, a flexible tube is attached to a video camera that is inserted into the abdominal cavity via small incisions. Fluid can also be collected during thoracoscopy or laparoscopy.

When the surgeon wishes to remove a larger tumor sample (or to remove it entirely), surgery will be recommended. In a thoracotomy, tissue is removed from the chest cavity. A laparotomy involves tissue taken from the abdominal cavity.

Oral Exploration
A bronchoscopy may be performed if pleural mesothelioma is suspected. In this process, the doctor inserts a flexible lighted tube down the trachea, and into the bronchi to check for masses in the airway. At that time, small samples of abnormal-appearing tissue may also be removed for testing.

Lymph Node Analysis
Lymph nodes are collections of immune system cells that help the body fight infection. By examining the lymph nodes, the doctor can determine if the cancer has spread. During a mediastinoscopy, a patient has a lighted tube inserted under the sternum (chest bone) at the neck level and then moved down into the chest. The surgeon can see the lymph nodes and take tissue samples to check for cancer. This procedure can also help the physician determine if you have lung cancer or mesothelioma.

Pulmonary Function
Pulmonary function tests (PFT’s) encompass a wide variety of tests that evaluate the entire respiratory system. The tests are useful in the assessment and diagnosis of pulmonary disease and aid in determining a course of treatment. PFTs can be a simple peak flow measurement, or complex body plethysmography and ventilation/perfusion scans which are performed in hospitals and clinics.

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Staging
Mesotheliomas are usually of three different cell types: 1) epithelial cell type - has the most favorable prognosis; 2) fibrosarcomatous cell type - carries the most negative prognosis and 3) mixed cell type - has an intermediate prognosis.

Using imaging studies such as MRI scans, x-rays and CT scans, physicians classify the spread (or “stage”) of cancer. Staging is important because it determines a patient’s course of treatment and for a better understanding of the prognosis. Pleural mesothelioma is the only mesothelioma for which a staging classification exists is because it occurs most frequently and has been studied the most.

The Butchart system is the most often used staging system for mesothelioma. This staging system is based primarily on the extent of the primary tumor mass and divides mesotheliomas into Stages I through IV. The following provides information on each stage and the most often associated treatment:

Localized Malignant Mesothelioma

• Stage I: cancer is present in the right or left pleura and may also exist in the lung, diaphragm, or pericardium.

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