T represents the size and spread of the tumor. Mesothelioma in all T stages involves one side of the membrane covering the lungs and lining the walls of the chest known as the pleura.
T1: cancer has spread to the pleura covering the lung;
T2: cancer has spread to the outer lining of the lung, the diaphragm, or the lung;
T3: cancer has spread into the first layer of the chest wall or a spot in the chest wall, the fatty part of the area between the sternum and the spinal column known as the mediastinum, or the outer layer of the heart;
T4: cancer has spread into the chest wall, through the diaphragm, into an organ within the mediastinum, into the spine, across to the opposite pleura, through the lining of the heart or into the heart, or into the nerves leading to the arm.
A physician can conduct a comprehensive medical history and physical examination to look for symptoms and risk factors related to mesothelioma. Shortness of breath, lower back pain, pain underneath the rib cage, abdominal swelling, hoarseness, and coughing up blood can be symptoms of mesothelioma. Asbestos exposure is a common risk factor for developing this cancer.
A chest x-ray photographs organs and bones inside the chest. This picture can show abnormalities of the pleura – the membrane that covers the lungs and lines the walls of the chest – which may assist in detecting mesothelioma. Computer tomography (CT) scans, positron emission tomography (PET) scans, and magnetic resonance imaging (MRI) scans are imaging tests that can offer additional information about the presence and severity of mesothelioma.
Mesothelioma can also be diagnosed through fluid tests and tissue samples. A biopsy can remove cells and/or tissues from the pleura to help determine whether they are cancerous.
The most prevalent risk factor for mesothelioma is asbestos exposure. Individuals who work around asbestos are at an increased risk of developing mesothelioma. Individuals who live with a person who works around asbestos may also have an increased risk because of asbestos dust being transferred from the work environment to the home environment through clothing and hair.
While tobacco use is not directly related to mesothelioma, individuals who smoke and are also exposed to asbestos have a greater chance of developing lung disease than non-smokers who are not exposed to asbestos.
Infection with simian virus 40 (SV40) may increase the risk of developing mesothelioma. The virus was inadvertently introduced into some of the polio vaccine during the late 1950s and early 1960s. Study findings about SV40 and a possible link to cancer are conflicting; consequently, further research needs to be conducted before concluding that a connection exists between the two.
Malignant mesothelioma can be categorized into pleural, peritoneal, or pericardial mesothelioma based on the location of the tumor.
Pleural mesothelioma – the most common form of malignant mesothelioma – is cancer of the thin membrane that covers the lungs and lines the walls of the chest; this membrane is called the pleura. The pleura function to assist the movement of the lungs during breathing.
A small percentage of malignant mesotheliomas originate in the abdomen. This form of the disease is referred to as peritoneal mesothelioma. The peritoneum is the lining that surrounds the stomach; it functions to protect the stomach by producing a lubricating fluid that allows the stomach to move freely during various activities.
Pericardial mesothelioma is a rare form of the disease that affects the lining of the heart, which is known as the pericardium.
There are three staging systems in staging mesothelioma, the Butchart System, the TNIM System, and the Brigham System. The oldest and most commonly used staging system is the Butchart System. This system contains four stages and bases the stages on the size of the primary tumor. Below, the four stages of the Butchart System are listed.
Stage I: Mesothelioma is occurring on either side of the pleura (right or left) and may include the diaphragm on that same side.
Stage II: Mesothelioma is occurring in the chest wall or occurring in the heart, esophagus, or bilateral pleura. There may be lymph node involvement at this stage.
Stage III: Mesothelioma is occurring in the diaphragm and into the lining of the peritoneum. There may be lymph node involvement at this stage.
Stage IV: Metastasis has occurred and the mesothelioma has spread through the bloodstream and into other organs.
Chest x-ray is the gold standard test in preliminary diagnosis of a pleural effusion, however, ultrasound, CT, and MRI scans are also used. After the preliminary diagnosis of a pleural effusion has been established, sampling of the fluid in the pleural cavity is necessary to proceed with any further diagnoses. Sampling of the fluid within the pleural cavity is called thoracentesis. However, only 15% of thoracentesis performed actually result in a positive diagnosis of mesothelioma. If after performing thoracentesis, a diagnosis can’t be made, a biopsy may need to be performed. Two types of biopsies are used, needle biopsy and open biopsy. A needle biopsy is performed under local anesthesia with a large hollow needle that is placed into the pleural cavity through the skin extracting a small amount of tissue. An open biopsy is performed under general anesthesia where a surgeon removes a larger area of tissue. Open biopsy is the most precise test in diagnosing mesothelioma.
The first symptoms of pleural mesothelioma are generalized and usually go unrecognized for quite sometime. Symptoms such as shortness of breath, persistent cough, and chest tightness/pain are common but, some patients are asymptomatic. These symptoms are usually caused by a pleural effusion. Pleural effusion is when fluid settles between the parietal and visceral pleura in the lungs. This happens due to the damage, by the cancer, to the mesothelial cells that make up the parietal and visceral pleura. The pleura, under healthy circumstances, should absorb any extra fluid formed in the pleural cavity, when cancer is present, normal fluid is not reabsorbed. There are two types of pleural effusions, transudates and exudates. The type of pleural effusion that presents in mesothelioma is exudative. As the pleural cavity continues to fill with fluid, patients present most commonly with shortness of breath, which then leads to a more thorough exam and more extensive testing.
Mesothelioma is cancer of the mesothelium, this occurs when the mesothelial cells become abnormal and disorganized due to uncontrolled cell dividing. The two most common types of mesothelioma are that of the pleura (a mesothelial membrane covering the lungs and the chest cavity surrounding the lungs), and the peritoneum (a mesothelial membrane covering the abdominal organs and the abdominal cavity). Pericardial mesothelioma is very uncommon, but does occur. Pleural and peritoneal mesothelioma, are linked with smoking and asbestos exposure, although it may take up to 50 years after exposure for symptoms to present. Mesothelioma is considered a locally invasive disease and can metastasize to other parts of the body via the bloodstream or the lymphatic system. Symptoms of mesothelioma vary upon location, stage and type. Once symptoms present, this cancer progresses very rapidly. Long term outcome is poor and treatment options are limited at this time.
The mesothelium is a membrane that protects several of the body’s internal organs. Special cells known as mesothelial cells make up the two layers of this unique, protective membrane. The first layer, or visceral layer, is directly connected to the organ in which it is protecting, the second layer or parietal layer, surrounds the organ as to form a pouch for protection. The mesothelial cells produce and release a lubricating fluid that decreases friction between organs and their neighboring structures. Examples of mesothelial membranes found in the body include, the pleura, found surrounding the lungs, the peritoneum, found in the stomach, the pericardium, found in the heart, the tunica vaginalis testis, found in the male testis, and the tunica serosa uteri, found in the female ovaries.
The location of the cancer, the stage of the disease, and the patient’s age will determine what type of treatment the patient will receive. Standard
treatment options include surgery, radiation therapy, and chemotherapy. These treatments are sometimes combined. Surgery is a common treatment for
mesothelioma. The physician may remove part or all of the affected tissue. Radiation involves the use of high-energy rays to kill cancer cells and
shrink tumors. Chemotherapy is the use of anticancer drugs to kill cancer cells throughout the body. To relieve symptoms and control pain, the
physician may use a needle or thin tube to drain fluid that has accumulated in the chest or abdomen. The procedure for removing fluid from the chest is
called a thoracentesis. Removal of fluid from the abdomen is called a paracentesis. Radiation therapy and surgery may also be helpful in relieving symptoms.