Mesothelioma Screening

Regular doctor appointments are crucial to ensure proper health, but exposure to asbestos presents added urgency to routine examinations. Asbestos-related diseases incubate for decades, and early detection is critical for proper treatment. People who worked in many industries such as construction, shipbuilding, and manufacturing are at particular risk of contracting these conditions.

Even the most talented and skilled doctors often mistake early symptoms of asbestos-related diseases for other, less hazardous conditions. Combined with the subtle nature of mesothelioma and a wealth of common symptoms, detection rests greatly on associating the proper symptoms with the proper diagnosis. Those with previous exposure to asbestos should alert their doctor to their medical history, so that doctors know what to look for and what tests to use.

How Mesothelioma Screening Works:

• Step 1: The first test a doctor will most likely run uses a device called a thorascope in a procedure called a thoracoscopy. Through a small incision in the chest, a small sample of lung tissue is taken for biopsy to determine whether or not it is cancerous. This procedure is done in a hospital under local anesthetic and usually causes little pain.
• Step 2: A doctor may also use a device called a peritoneoscope that looks inside the abdomen to collect tissue samples. Doctors also check for an excess amount of fluid and can elect to drain it to ease pressure and relieve pain.
• Step 3: Should these tests prove inconclusive, more advanced tests such as a Computed Axial Tomography (CAT) scan gives doctors a three dimensional X-Ray of the tissue in question. This allows doctors to view potentially damaged areas before they manifest symptoms.
• Step 4: Another option is called a Magnetic Resonance Imaging scan, or MRI. An MRI gives uses high energy magnetic fields to take cross-section pictures of internal structures to distinguish healthy tissues from malignant tissues. These two scans allow doctors to recognize dangers long before the patient feels any symptoms.

Credit to : http://www.resource4mesothelioma.com/

Mesothelioma Staging

Once malignant mesothelioma is found, more tests will be done to find out if cancer cells have spread to other parts of the body. This is called mesothelioma staging. A doctor needs to know the stage of the cancer to plan treatment.

Staging of mesothelioma is based on imaging studies such as x-rays, CT scans, and MRI scans. The treatment and outlook for patients with mesothelioma largely depends on the stage (extent of spread) of their cancer. Since pleural mesothelioma occurs most frequently and has been studied the most, it is the only mesothelioma for which a staging classification exists. The following stages are used for malignant mesothelioma:

Butchart Staging System

The staging system most often used for mesothelioma is the Butchart system. This system is based mainly on the extent of the primary tumor mass, and divides mesotheliomas into stages I through IV.

• Stage I: Mesothelioma is present within the right or left pleura, and may also involve the lung, pericardium, or diaphragm (the muscle separating the chest from the abdomen) on the same side.
• Stage II: Mesothelioma invades the chest wall or involves the esophagus (food passage connecting the throat to the stomach), heart, or pleura on both sides. The lymph nodes in the chest may also be involved.
• Stage III: Mesothelioma has penetrated through the diaphragm into the peritoneum (lining of the abdominal cavity). Lymph nodes beyond those in the chest may also be involved.
• Stage IV: There is evidence of distant metastases (spreading of cancerous cells via the bloodstream to other organs).

TNM Staging System

Another staging system has recently been developed by the American Joint Committee on Cancer (AJCC). This is a TNM system, similar to staging systems used for most other cancers. T stands for tumor (its size and how far it has spread to nearby organs), N stands for spread to lymph nodes and M is for metastasis (spread to distant organs). In TNM staging, information about the tumor, lymph nodes, and metastasis is combined in a process called stage grouping to assign a stage described by Roman numerals from I to IV. Minor differences exist between the AJCC TNM staging system and the Butchart staging system.

• Stage I: Mesothelioma involves the right or left pleura. It may also have spread into the lung, pericardium, or diaphragm on the same side. It has not yet spread to the lymph nodes.
• Stage II: Mesothelioma has spread from the pleura on one side to the nearby peribronchial and/or hilar lymph nodes next to the lung on the same side. It may also have spread into the lung, pericardium, or diaphragm on the same side.
• Stage III: Mesothelioma has spread into the chest wall muscle, ribs, heart, esophagus, or other organs in the chest on the same side as the primary tumor, with or without spread to subcarinal and/or mediastinal lymph nodes on the same side as the main tumor. Subcarinal nodes are located at the point where the windpipe branches to the left and right lungs. Mediastinal lymph nodes are located in the space behind the chest bone in front of the heart. Mesotheliomas with the same extent of local spread as in Stage II that have also spread to subcarinal and/or mediastinal lymph nodes on the same side are also included in Stage III.
• Stage IV: Mesothelioma has spread into the lymph nodes in the chest on the side opposite that of the primary tumor, or directly extends to the pleura or lung on the opposite side, or directly extends into the peritoneum, or directly extends into organs in the abdominal cavity or neck. Any mesothelioma with evidence of distant metastases (spreading to other organs via the bloodstream) or spread to organs beyond the chest or abdomen is included in this stage.

Although the recently developed TNM classification is the most detailed and precise, the original Butchart staging system is still used most often to describe the spread of pleural mesotheliomas. Understanding these staging systems for mesothelioma is important both for estimating and better understanding prognosis, and also for assessing therapeutic options. | http://mesothelioma-net.org

Diagnosing mesothelioma

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.

Typical immunohistochemistry results
Positive	Negative
EMA (epithelial membrane antigen) in a membranous distribution	CEA (carcinoembryonic antigen)
WT1 (Wilms' tumour 1)	B72.3
Calretinin	MOC-3 1
Mesothelin-1	CD15
Cytokeratin 5/6	Ber-EP4
HBME-1 (human mesothelial cell 1)	TTF-1 (thyroid transcription factor-1)

There are three histological types of malignant mesothelioma: (1) Epithelioid; (2) Sarcomatoid; and (3) Biphasic (Mixed). Epithelioid comprises about 50-60% of malignant mesothelioma cases and generally holds a better prognosis than the Sarcomatoid or Biphasic subtypes

Cause of malignant mesothelioma

Working with asbestos is the major risk factor for mesothelioma. In the United States, asbestos is the major cause of malignant mesothelioma and has been considered "indisputably" associated with the development of mesothelioma. Indeed, the relationship between asbestos and mesothelioma is so strong that many consider mesothelioma a “signal” or “sentinel” tumor. A history of asbestos exposure exists in most cases. However, mesothelioma has been reported in some individuals without any known exposure to asbestos. In rare cases, mesothelioma has also been associated with irradiation, intrapleural thorium dioxide (Thorotrast), and inhalation of other fibrous silicates, such as erionite. Some studies suggest that simian virus 40 (SV40) may act as a cofactor in the development of mesothelioma.

Asbestos was known in antiquity, but it was not mined and widely used commercially until the late 19th century. Its use greatly increased during World War II. Since the early 1940s, millions of American workers have been exposed to asbestos dust. Initially, the risks associated with asbestos exposure were not publicly known. However, an increased risk of developing mesothelioma was later found among shipyard workers, people who work in asbestos mines and mills, producers of asbestos products, workers in the heating and construction industries, and other tradespeople. Today, the official position of the U.S. Occupational Safety and Health Administration (OSHA) and the U.S. EPA is that protections and "permissible exposure limits" required by U.S. regulations, while adequate to prevent most asbestos-related non-malignant disease, they are not adequate to prevent or protect against asbestos-related cancers such as mesothelioma. Likewise, the British Government's Health and Safety Executive (HSE) states formally that any threshold for mesothelioma must be at a very low level and it is widely agreed that if any such threshold does exist at all, then it cannot currently be quantified. For practical purposes, therefore, HSE assumes that no such "safe" threshold exists. Others have noted as well that there is no evidence of a threshold level below which there is no risk of mesothelioma. There appears to be a linear, dose-response relationship, with increasing dose producing increasing disease. Nevertheless, mesothelioma may be related to brief, low level or indirect exposures to asbestos. The dose necessary for effect appears to be lower for asbestos-induced mesothelioma than for pulmonary asbestosis or lung cancer. Again, there is no known safe level of exposure to asbestos as it relates to increased risk of mesothelioma.

The duration of exposure to asbestos causing mesothelioma can be short. For example, cases of mesothelioma have been documented with only 1–3 months of exposure.People who work with asbestos wear personal protective equipment to lower their risk of exposure.

Latency, the time from first exposure to manifestation of disease, is prolonged in the case of mesothelioma. It is virtually never less than fifteen years and peaks at 30–40 years. In a review of occupationally related mesothelioma cases, the median latency was 32 years. Based upon the data from Peto et al., the risk of mesothelioma appears to increase to the third or fourth power from first exposure. | Wikipedia

Symptoms and signs of mesothelioma

Symptoms or signs of mesothelioma may not appear until 20 to 50 years (or more) after exposure to asbestos. Shortness of breath, cough, and pain in the chest due to an accumulation of fluid in the pleural space (pleural effusion) are often symptoms of pleural mesothelioma.

Symptoms of peritoneal mesothelioma include weight loss and cachexia, abdominal swelling and pain due to ascites (a buildup of fluid in the abdominal cavity). Other symptoms of Peritoneal Mesothelioma may include bowel obstruction, blood clotting abnormalities, anemia, and fever. 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.

These symptoms may be caused by mesothelioma or by other, less serious conditions.

Mesothelioma that affects the pleura can cause these signs and symptoms:

• Chest wall pain
• Pleural effusion, or fluid surrounding the lung
• Shortness of breath
• Fatigue or anemia
• Wheezing, hoarseness, or cough
• Blood in the sputum (fluid) coughed up (hemoptysis)

In severe cases, the person may have many tumor masses. The individual may develop a pneumothorax, or collapse of the lung. The disease may metastasize, or spread, to other parts of the body.

Tumors that affect the abdominal cavity often do not cause symptoms until they are at a late stage. Symptoms include:

• Abdominal pain
• Ascites, or an abnormal buildup of fluid in the abdomen
• A mass in the abdomen
• Problems with bowel function
• Weight loss

In severe cases of the disease, the following signs and symptoms may be present:

• Blood clots in the veins, which may cause thrombophlebitis
• Disseminated intravascular coagulation, a disorder causing severe bleeding in many body organs
• Jaundice, or yellowing of the eyes and skin
• Low blood sugar level
• Pleural effusion
• Pulmonary emboli, or blood clots in the arteries of the lungs
• Severe ascites

A mesothelioma does not usually spread to the bone, brain, or adrenal glands. Pleural tumors are usually found only on one side of the lungs.

Definition of Mesothelioma

Mesothelioma, more precisely malignant mesothelioma, is a rare form of cancer that develops from the protective lining that covers many of the body's internal organs, the mesothelium. It is usually caused by exposure to asbestos.

Its most common site is the pleura (outer lining of the lungs and internal chest wall), but it may also occur in the peritoneum (the lining of the abdominal cavity), the pericardium (a sac that surrounds the heart), or the tunica vaginalis (a sac that surrounds the testis).

Most people who develop mesothelioma have worked on jobs where they inhaled asbestos, or they have been exposed to asbestos dust and fiber in other ways. It has also been suggested that washing the clothes of a family member who worked with asbestos can put a person at risk for developing mesothelioma. Unlike lung cancer, there is no association between mesothelioma and smoking, but smoking greatly increases the risk of other asbestos-induced cancers.Those who have been exposed to asbestos have collected damages for asbestos-related disease, including mesothelioma. Compensation via asbestos funds or lawsuits is an important issue in law practices regarding mesothelioma (see asbestos and the law).

The symptoms of mesothelioma include shortness of breath due to pleural effusion (fluid between the lung and the chest wall) or chest wall pain, and general symptoms such as weight loss. The diagnosis may be suspected with chest X-ray and CT scan, and is confirmed with a biopsy (tissue sample) and microscopic examination. A thoracoscopy (inserting a tube with a camera into the chest) can be used to take biopsies. It allows the introduction of substances such as talc to obliterate the pleural space (called pleurodesis), which prevents more fluid from accumulating and pressing on the lung. Despite treatment with chemotherapy, radiation therapy or sometimes surgery, the disease carries a poor prognosis. Research about screening tests for the early detection of mesothelioma is ongoing.