There are some factors that can increase your risk of developing mesothelioma, they are explained below. But having any of these risk factors doesn’t mean you will definitely get cancer.
We know that asbestos causes most cases of pleural mesothelioma. The risk is greater if you were exposed to large amounts of it from for a very long period of time. Many people with mesothelioma in the abdomen (peritoneal mesothelioma) have also been exposed to asbestos.
The link with mesothelioma and asbestos has only been known since the 1960s. Unfortunately, the number of cases of mesothelioma in the UK each year is expected to rise sharply for the next few years. This is because of the heavy use of asbestos in industry from the end of the second world war up until the mid 1970s.
Mesothelioma is quite a rare cancer, and it is estimated that in the UK, more than 9 out of 10 men with mesothelioma, and more than 8 out of 10 women with this type of cancer have been in contact with asbestos. But some people with mesothelioma say they have no history of any exposure to asbestos.
What asbestos is
Asbestos is an insulating material that’s heat and fire resistant. The use of asbestos was banned in 1999 in the UK. It was widely used in:
- building industry
- manufacturing of household appliances
- motor industry
- power stations
- telephone exchanges
There are three main types of asbestos – blue, brown and white. Blue and brown asbestos are strongly linked with mesothelioma and have been banned in the UK since the late 1980s. White asbestos is now also thought to be harmful.
How asbestos causes mesothelioma
Asbestos is made up of tiny fibres. You can breathe these fibres in when you come into contact with asbestos.
The fibres work their way into the pleura lining the lung. They irritate the pleura and may cause gene changes (mutations) that lead to the growth of cancer. Some of the fibres can be coughed up and swallowed. This is probably the cause of peritoneal mesothelioma.
There is some evidence that families of people exposed to asbestos have a higher risk of developing mesothelioma as asbestos fibres can be carried home on clothes.
Highest risk groups
Mesothelioma is most common in those who have been exposed to asbestos at work, for example, they have:
- worked in manufacturing using asbestos
- used asbestos products, particularly in construction or engineering
This could be in a range of jobs including metal plate workers (mainly in shipbuilding), carpenters, plumbers and mechanics.
Smoking also increases the risk of cancer in people who have been exposed to asbestos.
Asbestos was widely used in the years after the war (after 1945). Mesothelioma may not develop until 15 to 60 years after you have been exposed to asbestos, which is why we have seen an increase in cases in recent years. The number of people dying from mesothelioma each year is expected to peak around 2020 and then start to go down.
Research has looked into a virus called SV40 (the SV stands for simian virus) but there is not enough evidence to suggest the infection is linked with mesothelioma risk.
In people who have been exposed to asbestos, contact with the SV40 virus could make it more likely that they will develop mesothelioma. So SV40 is thought of as a possible co factor. But this is not completely clear.
Some people in the UK and elsewhere were exposed to polio vaccines contaminated with SV40 virus between 1955 and 1963.
Pleural and peritoneal mesothelioma has been shown to develop after exposure to radiation from the chemical thorium dioxide (Thorotrast). This chemical was used until the 1950s in some x-ray tests.
Some research studies show an increased risk of mesothelioma in people treated with radiotherapy for a previous cancer. But other studies show no increased risk. If radiotherapy does increase the risk of mesothelioma, this is likely to happen only in a very small number of people.
Working as a painter has been linked with an increased risk of mesothelioma, possibly due to chemicals in the paints, or in work sites.
A mineral similar to asbestos called erionite has been found to increase risk of mesothelioma in Turkey, but this has not been found in populations elsewhere.
Other possible causes
Stories about potential causes of cancer are often in the media. It isn’t always clear which ideas are supported by good evidence.
You might hear about possible causes we haven’t included here. This is because there is no evidence about them or because the evidence isn’t clear.