Malignant mesothelioma is the most serious type of the various diseases caused by
asbestos.
There are up to 3,000 new cases of malignant mesothelioma diagnosed each
year in the United States alone (where asbestos has been regulated since 1970) and
the disease is believed to be responsible for more than 200,000 deaths worldwide.
Malignant mesothelioma is a somewhat rare type of cancer that has been
linked exclusively with asbestos exposure. With most cancers doctors can only
talk about an increase in risk called a risk factor but there is no causal link.
With mesothelioma the link is so strong that the medical literature states that
asbestos causes mesothelioma, rather than just saying it is a risk factor.
There are three types of mesothelioma, each affecting a different section
of mesothelial tissue:
- Pleural mesothelioma is the most common type of
malignant mesothelioma (accounting for an approximately 70 to 80% of all documented
cases), affecting the mesothelial tissue lining the lung cavity (pleura).
- Peritoneal mesothelioma is the second most common
type of malignant mesothelioma (roughly 10% to 20% of all documented cases) affecting
the mesothelial tissue lining the abdominal cavity (peritoneum).
- Pericardial mesothelioma is a less common type
of malignant mesothelioma (accounting for less than 10% of all documented cases),
affecting the mesothelial tissue lining the heart sac (pericardium).
-
Tunica vaginalis testi mesothelioma is a
very rare form of malignant mesothelioma affecting the mesothelial tissue lining
the testicles. It is sometimes refered to as gonadal mesothelioma.
Cigarette smoking causes most lung cancers, but long term exposure to
asbestos is also a cause of lung cancer. People who smoke and have been exposed
to asbestos have a very high risk of developing the disease.
There are two main types of lung cancer. Small cell lung carcinoma is common to
smokers. Non-small cell lung carcinoma has three main forms, including:
- Squamous cell carcinoma the most common form of lung cancer. This starts in the
large air passages, called bronchi.
- Large cell carcinoma similar to squamous cell carcinoma.
- Adenocarcinoma starts in glands found in the lining of the airways.
Asbestosis is a chronic inflammatory medical condition affecting the parenchymal
tissue of the lungs. It occurs after long-term, heavy exposure to asbestos,
e.g. in mining, and is therefore regarded as an occupational lung disease. Sufferers
have severe dyspnea (shortness of breath) and are at an increased risk regarding
several different types of lung cancer.
As clear explanations are not always stressed in non-technical literature, care
should be taken to distinguish between several forms of relevant diseases.
According to the World Health Organisation (WHO), these may be defined as; asbestosis
(the subject of this article), lung cancer, and mesothelioma (generally a very rare
form of cancer, but increasing in frequency as people exposed to asbestos age).
Diffuse pleural thickening of the tissue surrounding
the lungs and other organs is less specific to asbestos exposure than for pleural
plaque development. Thickening and fibrosis of the visceral pleura occurs with fusion
to the parietal pleura over a wide area.
Diffuse pleural thickening may result from exudative
pleural effusions secondary to asbestos exposure, but other causes of pleural disease
may also cause thickening (e.g. haemothorax, connective tissue diseases, tuberculosis,
chest surgery, drugs such as methysergide and parapneumonic effusions).
