Mesothelioma cancer is a type of cancer that attacks the lungs and chest cavity. Also known as asbestos lung cancer, it forms deadly tumors where mesothelial cancer cells form a protective lining over the lungs, heart, and abdominal organs. It is a type of lung cancer that takes many years to develop and produce symptoms. Roughly 3,000 cases per year (mostly men over the age of 40) are reported. It is estimated that number will grow to about 300,000 cases before 2030.
Types of Mesothelioma Asbestos Cancer
Epithelial mesothelioma is a rare and fatal form of cancer affecting the membrane lining of the chest cavity, heart, lungs, and abdominal cavity. There are three forms of epithelial mesothelioma: the most common is Pleural Mesothelioma, the second most common, Peritoneal Mesothelioma (accounting for only a quarter of the cases), and the rarest form, pericardial mesothelioma.
Pleural mesothelioma, the most common type of this disease involves the pleura, a thin membrane located between the lungs and the chest cavity. The pleura provide a lubricated surface so that the lungs do not rub and chafe against the chest walls. There are two types of pleural mesothelioma the first being ‘diffuse and malignant’. This type is cancerous and is generally fatal within a year of diagnosis. The second type is ‘localized and benign’ and is generally non-life threatening. It can usually be removed through surgery.
Lung Lining cancer is not to be confused with lung cancer. In lung lining cancer, the effected area of the body is called the mesothelium, a thin membrane that covers many of the internal organs of the body. The mesothelium of the lungs is called the pleura. Lung Lining cancer is also sometimes called mesothelioma after the area in which it occurs.
This thin membrane is comprised of two layers – one that surrounds the organ and another that forms an exterior sac around the first layer. Between the layers of the mesothelium is a fluid that allows vital organs to glide easily against objects that come in contact with them.
Localized pleural mesothelioma is not always caused by asbestos exposure. However, if it has spread to other parts of the body, for instance the lymph nodes, lungs, chest wall, or abdominal organs, then it is considered malignant and is more often than not the result of asbestos exposure.
Peritoneal mesothelioma appears as a tumor in the peritoneum membrane of the abdomen. This type of mesothelioma is very rare, comprising less than a fourth of all known cases of the disease. There are no effective treatments for this condition, and most patients live less than a year after diagnosis.
Mesentery cancer is likened to peritoneal cancer (mesothelioma). This cancer primarily affects the sections of the peritoneum that attach different organs to the wall of the abdominal cavity, (i.e. mesogastrium for the stomach, mesojejunum for the jejunum). Mesentery cancer includes all abdominal peritoneal extensions. Tumors rarely originate in the actual mesentery, though it is a frequent route for the spread of mesothelioma through the abdominal cavity.
Pericardial mesothelioma is the rarest form of mesothelioma, affecting the membrane around the heart (called the pericardium or pericardial sac). In this disease, solid masses and effusion (fluid) develop around the pericardium. Not all effusions are strictly related to mesothelioma.
Mesothelioma cancer is caused by exposure to asbestos fibers or dust. Workers in the asbestos industry are prime targets for attracting this deadly disease. Asbestos fibers enter the body, either by breathing in the tiny asbestos fibers or by swallowing them. The fibers cause healthy cells to mutate into cancer. Since the body is unable to dispel these fibers, the lungs become inflamed (asbestosis). This condition worsens and eventually becomes malignant. Asbestos exposure is thought to be responsible for roughly 75% of all cases of lung lining cancer.
Mesothelioma is a very difficult cancer to detect in early stages. The early symptoms tend to be generic and even nonexistent in some cases, and it can take as much as 15 to 50 years after exposure to develop. The first symptom is often constant chest pain, followed by coughing, lung damage, and shortness of breath. Patients who have peritoneal mesothelioma (a less common form of mesothelioma) generally experience abdominal pain, loss of appetite, nausea, and abdominal swelling, often in addition to the symptoms of pleural mesothelioma. They may also develop bowel obstruction or further breathing obstruction.
Stages and Diagnosis of Mesothelioma
There are three staging systems used to determine treatment for mesothelioma: Butchart System, TNM System, and the Brigham System
Butchart Staging System
The Butchart System is the oldest system and the most common. This system concentrates upon determining the extent of primary tumor mass and divides mesothelioma into four stages.
Stage I of the Butchart System consists of the presence of mesothelioma in the lining of the right or left lung and may also involve the diaphragm on the same side. Stage II includes the progression of mesothelioma into the chest wall, esophagus, or lung lining on bother sides. There may also be lymph nodes in the chest. The onset of Stage III begins when the mesothelioma surpasses the diaphragm into the lining of the abdominal cavity or peritoneum. In this stage the cancer may also affect the lymph nodes extending beyond those in the chest. Doctors identify Stage IV, the final stage, when evidence of the spread of cancer to other organs (metastasis) is confirmed.
Stage I of the TNM System involves the lining of the right or left lung, pericardium, or diaphragm on the same side. At this stage, lymph nodes are not involved. Stage II begins when mesothelioma spreads from the lining of the lung on one side to a lymph node on the same side. At this stage, the cancer may also spread to the lung, pericardium, or diaphragm on the same side. Stage III begins when mesothelioma is present in the chest wall, muscle, ribs, heart, esophagus, or other organs in the chest on the same side as the primary tumor. In the final stage, Stage IV, the mesothelioma has travelled into the lymph nodes in the chest on the side opposite the primary tumor, into the lung opposite the primary tumor, or directly into the organs in the abdominal cavity or neck. Metastasis is the final result in this stage.
The Brigham System determines the resectability (the ability to surgically remove) the mesothelioma mass. In Stage I the tumor is resectable, while lymph nodes remain unaffected. In Stage II the tumor remains respectable but the mesothelioma affects the lymph nodes. In Stage III the tumor becomes unresectable. It has penetrated through the diaphragm, or peritoneum. Stage III can occur with or without lymph involvement and extends into the chest wall and heart. Stage IV occurs when doctors discover metastatic disease involving distant organs.
After doctors identify the stage of a patient’s malignant mesothelioma, the patient and doctor consider the various treatment options available. Mesothelioma treatment programs are contingent upon many factors, including the stage of the cancer, the location of the cancer, the spread of mesothelioma cancer, the characteristics of the cancer cells under a microscope and the patient’s age and concerns.