Malignant mesothelioma is a deadly, but rare form of cancer that develops in the thin membrane that protect most organs in the body including the lungs, heart, and the abdomen. Research has indicated that malignant mesothelioma is caused by exposure to asbestos 1,2,3, that’s the reason it’s sometimes referred to as asbestos cancer. People who think they may have been exposed to asbestos at workplace, at home, or other environments, they need to seek medical help for early screening. One big problem that has been seen with mesothelioma is it’s latency period – it has a long period for it to be diagnosed something that has made its prognosis to be poor and the life expectancy to be short.1
As of today, exposure to asbestos may be said to be the only known cause of malignant mesothelioma. People who ingest or inhale asbestos will have the microscopic fibers getting lodged in the lining tissue of organs like the abdomen and chest.
In March 2009, IARC or the International Agency for Research on Cancer reconfirmed that the leading cause of malignant mesothelioma is asbestos exposure, and all asbestos forms cause the cancer. About two years after this reconfirmation, IARC did a presentation showing the connection between cancer and asbestos at WHO conference in Spain. In the presentation, IARC said that scientific evidence confirming asbestos exposure as the main cause of mesothelioma has been strengthening over time.1
Talking of asbestos, it’s a naturally occurring mineral that has been used for many centuries. It has been used in products including insulation and textiles. The mineral saw an increased usage in early to mid of 20th century recording its peak of usage in USA during the Second World War. Not until 1980s was its commercial usage stopped.1
Despite the curb of using asbestos for commercial applications, people are still likely to be exposed to the mineral. This substance consists of flexible, microscopic fibers deemed to be lighter than air, but with high tensile strength. A fiber of asbestos is considered to be a hundred or so times thinner when compared to the human hair.
Uses of Asbestos
The substance has high resistance to corrosion, water, and heat damage, and this is one reason why it gained popularity in usage within a range of industries and applications including building insulation, brake pads for cars, and gaskets.
Types of Asbestos
The main categories of asbestos are amphibole and serpentine, and they are categorized by the shape the fibers assume. Serpentine has wavy fibers and is said to be found in about 95% of products developed for commercial use in USA. Since serpentine fibers are light and wavy, they can easily be breathed out from an individual’s body when compared to amphibole fibers. 1,2,3,4
The other main category, which is amphibole consists of spindle-shaped fibers that tend to be rigid, sharp, and have the ability to lodge themselves in the tissue of the body. It is this property of amphibole that increases the risk of an individual developing mesothelioma.
Besides the two categories, there are six types of the mineral, but two of them namely: tremolite and actinolite, are not used commercially. The other four, and which are found in many products and materials are:1,2,3
- These appear gray and are used in different commercial applications
Crocidolite and Amosite
These appear blue and brown respectively, and they are used in spray-on insulation and on ships. Both of these types of asbestos take a brittle, needle-like structure making them to be difficult to dislodge or come out of the respiratory tract.
These are white in appearance and are a form of serpentine asbestos (the only serpentine asbestos we have). Chrysotile has curled fibers and it’s one of the most used in commercial applications. These asbestos fibers can be dislodged from a person’s body much easier compared to the other forms.
Kinds of Asbestos Exposure
People may be exposed to asbestos in different ways including:1
This involved people being directly exposed to the mineral at their jobs. People who worked in construction or industrial trades or those who came in contact with products used in these applications may have been exposed to the fibers. Another name for occupational exposure is first hand exposure to asbestos.
There are cases where people were exposed to the mineral after coming in contact with clothes of persons who worked with or near the substance.
Because the mineral may be found in nature, for example in mines, it means that people near those locations may have been exposed to the fibers released into the air.
How Does Asbestos Cause Mesothelioma?
Various studies explore the way in which asbestos causes mesothelioma. An expert in mesothelioma Dr. Michele Carbone who is also the director of thoracic oncology within the University of Hawaii Center did feature in co-writing a scientific piece in 2012 that detailed the various ways asbestos could damage an individual’s body.
In the publication, Dr. Michele Carbone said that asbestos may damage the body by creating inflammatory chemicals that bring about direct genetic damage. Of course, there are other theories that try to highlight how this substance is likely to cause malignant mesothelioma.2
The development of mesothelioma may not occur with little exposure to asbestos, it usually has to be a heavy, long-term exposure. That said, even minor exposures may be harmful. If products containing asbestos fibers are disturbed, they release the mineral into the air, and because there is a dose-response relationship for mesothelioma to asbestos, it means that exposing yourself to high doses of the substance leads to greater risks of having mesothelioma.
In the body, asbestos may build up in organs like the lungs and areas such as the abdomen because the fibers are sharp or even jagged shaped for them to be expelled out of the body. After a long time of having asbestos exposure, a person may begin to have cancerous changes that start in mesothelial cells comprising the tissue lining the heart, lungs, and abdomen.2
Theories on Development of Asbestos Related Tumors
There are different schools of thought when it comes to the way asbestos may cause tumor development and they include:
When the asbestos fibers get into the mesothelial cells, they cause disruption on the life cycle of the cells something that induces changes in DNA leading to development of cancer.
The fibers may cause irritation and inflammation of the mesothelial cells leading to irreversible scarring, damage to the cellular structure, and development of cancer.
The fibers lead to free radicals in body, which cause damage to the DNA making healthy cells to mutate and become cancerous.
The asbestos fibers may trigger the release of oncoproteins, and these kinds of proteins block genes responsible in protecting the cells from uncontrollably growing and forming tumors.
When you look at these theories, you will find a common ground that asbestos fibers change the life cycle of cells.
Healthy cells have genes able to regulate and protect the body against cancer and when the asbestos block this function, you may find the cells begin to divide uncontrollably leading to formation of malignant tumors whether localized or metastasized. The tumors tend to develop later on when mesothelioma has already started, but it’s one of the clinical symptoms of the cancer. Some types of asbestos are more carcinogenic compared to others, for example crocidolite and amosite.
- CAUSES OF MESOTHELIOMA. Available at https://www.mesotheliomagroup.com/mesothelioma/causes/
- Mesothelioma Causes & Risk Factors. Available at https://www.asbestos.com/mesothelioma/causes.php
- Asbestos Cancer. Available at https://www.mesothelioma.com/asbestos-cancer/
- Asbestos – The Primary Cause of Mesothelioma. Available at https://www.mesotheliomaguide.com/mesothelioma/causes/asbestos/