Asbestos cancer or Mesothelioma is a type of cancer that is almost always caused by previous exposure to asbestos. Hence it is also termed as Asbestos Cancer. In this disease, malignant (cancerous) cells develop in the mesothelium, a protective lining that covers most of the body’s internal organs.
Its most common site is the pleura (outer lining of the lungs and chest cavity), but it may also occur in the peritoneum (the lining of the abdominal cavity) or the pericardium (a sac that surrounds the heart).
Majority of the people who develop asbestos cancer or mesothelioma have worked on jobs where they inhaled asbestos particles. This is direct exposure.
On the other side some people might have been exposed to asbestos dust and fiber in other ways, such as by washing the clothes of a family member who worked with asbestos, or by home renovation using asbestos cement products. There is no association between asbestos cancer or mesothelioma and smoking.
Malignant mesothelioma or asbestos cancer is an uncommon, but no longer rare, cancer that is difficult to diagnose and poorly responsive to therapy. Malignant mesothelioma is the most serious of all asbestos-related diseases.
A layer of specialized cells called mesothelial cells lines the chest cavity, abdominal cavity, and the cavity around the heart. These cells also cover the outer surface of most internal organs. The tissue formed by these cells is called mesothelium.
The mesothelium helps protect the organs by producing a special lubricating fluid that allows organs to move around. For example, this fluid makes it easier for the lungs to move inside the chest during breathing.
The mesothelium of the chest is called the pleura and the mesothelium of the abdomen is known as the peritoneum. The mesothelium of the pericardial cavity (the “sac-like” space around the heart) is called the pericardium.
Tumors of the mesothelium can be benign (noncancerous) or malignant (cancerous). A malignant tumor of the mesothelium is called a malignant mesothelioma. Because most mesothelial tumors are cancerous, malignant mesothelioma is often simply called mesothelioma.
Cause of Asbestos Cancer or Mesothelioma
Asbestos exposure is the main cause of asbestos cancer or mesothelioma. After these fibers are breathed in, they travel to the ends of small air passages and reach the pleura where they cause physical damage to mesothelial cells that may result in asbestos cancer.
In addition, they also cause injury to lung cells that can result in lung cancer and/or asbestosis (replacement of lung tissue by scar tissue). If swallowed, these fibers can reach the abdominal cavity where they have a role in causing peritoneal mesothelioma.
Exposure to asbestos, though mostly occupational, can also be environmental or familial by household contamination, through the work clothes of an asbestos worker for instance.
Beginning 15 years after the onset of exposure, about 6% of asbestos workers die of mesothelioma or asbestos cancer. In one study of asbestos insulation workers, the death rate from asbestos cancer or mesothelioma was 344 times higher than in the general population. (Selifoff IJ et al. Relation between exposure to asbestos and mesothelioma. NEJM)
The only known cause of mesothelioma is previous exposure to asbestos fibers. Often time’s workers are not told they are working around asbestos, and even single exposures to very low doses of fibers can produce serious long-term consequences.
Asbestos diseases are said to follow the trail of exposure. That means that wherever people have received asbestos exposure, regardless of their trade, age, sex or race, they are at risk of asbestos cancer and other diseases.
Almost anyone who has inhaled asbestos dust is at risk. Even a worker’s families and friends can be at risk, because asbestos can often be carried on clothing.
Exposure to asbestos dust can occur at major construction job sites, in shipyards, in industry, and during construction or renovation of commercial buildings.
Risk factors for Asbestos Cancer or Mesothelioma
A risk factor is anything that increases a person’s chance of getting a disease such as cancer. Different cancers have different risk factors. For example, unprotected exposure to strong sunlight is a risk factor for skin cancer and smoking is a risk factor for asbestos cancer or mesothelioma as well as other types of cancer. Scientists have found several risk factors that make a person more likely to develop mesothelioma or asbestos cancer.
As the name suggests the main risk factor for developing asbestos cancer or mesothelioma is exposure to asbestos. Asbestos refers to a family of magnesium-silicate mineral fibers. In the past, asbestos was used widely for insulation because it does not conduct heat well and it is resistant to melting or burning. As the link between asbestos and mesothelioma has become well known, the use of this material has decreased.
There have been a few published reports of pleural and peritoneal mesotheliomas that developed following exposure to thorium dioxide (Thorotrast). This material was used in the past by doctors for certain x-ray tests. Because Thorotrast was found to cause cancers, it has not been used for many years.
This is a silicate mineral, chemically related to asbestos, common in the soil of the Anatoli region of Turkey. A few cases of asbestos cancer or mesothelioma have been described in this region and may have been caused by this mineral.
Although tobacco smoking has not been associated with the development of asbestos cancer or mesotheliomas, the combination of smoking and asbestos exposure greatly increases the risk of lung cancer. Asbestos workers who also smoke have a lung cancer risk 50 to 90 times greater than that of the general population. More asbestos workers die of lung cancer than of asbestos cancer or mesothelioma.
Symptoms of Asbestos Cancer or Mesothelioma
Early symptoms of asbestos cancer or mesothelioma are not specific to the disease. People often ignore them or mistake them for common, minor ailments. Most people with asbestos cancer or mesothelioma have symptoms for only 2 to 3 months before they are diagnosed. About one-fourth have symptoms for at least six months prior to their diagnosis.
Over half of patients with pleural mesothelioma have
- Pain in the lower back or at the side of the chest
- Shortness of breath.
- Difficulty in swallowing
- Weight loss
Other symptoms include hoarseness, coughing up blood, swelling of the face and arms, muscle weakness, and sensory loss.
Symptoms of peritoneal mesothelioma include
- Abdominal (belly) pain
- Weight loss
- Hernia, fluid in the abdominal cavity
- A mass in the abdomen.
Role of Asbestos in Mesothelioma
The generic name “asbestos” belongs to a group of minerals called “asbestiform” minerals. Asbestos is a fibrous material which is mined from serpentine rock.
Basically, rock was mined and crushed. When the rock was crushed, fibrous stands of asbestos were extracted from the rock. The strands where put in bags and shipped to manufacturing facilities were the asbestos was used as an ingredient in insulation and other materials. The three most commonly used forms of asbestos in product manufacturing were chrysotile, amosite and crocidolite.
Although asbestos products have not been used in construction since approximately 1975, the products in place present a clear danger to individuals involved in repair work and the demolition of structures containing asbestos products.