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Mesothelioma is most often linked to exposure to asbestos.

So much of the research into this disease is based on finding out exactly how asbestos affects the normal cells of the lining of the chest and abdominal cavities. If we can have a better understanding of how asbestos fibres cause cancer and how exposure to this chemical affects us, then we may be able to help prevent the disease.

Researchers know that there can be an incredibly long time lag between exposure to asbestos and developing mesothelioma. It can be 40 years or more. This probably meant that it took longer to spot the connection between asbestos and cancer than it otherwise would. But we know now, and the use of asbestos in many countries is now illegal. There has been talk for the past few years about a link between a virus called the simian virus (SV40) and developing mesothelioma. Some polio vaccine preparations were contaminated with SV40 between 1955 and 1963 and doctors were concerned that people who'd had them may be at increased risk. One large study has indicated that these people are not at an increased risk of mesothelioma or other types of cancers. The study was published in 2003 and found that mesothelioma rates were actually falling in this group of people. The link between SV40 and mesothelioma (if there is one) is likely to be much less important than the link with asbestos.

There is some evidence that your genetic make up could affect your risk of mesothelioma. As well as asbestos, exposure to a mineral called erionite is a risk factor. Researchers in Turkey found that in families exposed to this mineral, in some families all the family members developed mesothelioma and in other families, no one developed it. They think that there is a gene in some families in Turkey that increases their risk. (This article is published in The Lancet, volume 357, issue 9254, page 444.) This could explain why some people are exposed to asbestos and do not develop mesothelioma, while others who are exposed do. There is a lot more research to be done before we will know if there are specific gene changes that can increase your risk of mesothelioma. It will be some years after this has been completed before there will be any chance of testing for such a gene. In the past, asbestos was used widely in the •Building industry •Ship building industry •Manufacture of household appliances •Motor industry

Finding a tumour marker for mesothelioma
Mesothelioma can be very difficult to diagnose. This is because there are many different types of cells that can make up a mesothelioma tumour. Mesothelioma tumour cells are very similar to some types of lung cancer cells. Sometimes it can be very difficult for a pathologist to decide whether or not the cancerous cells are mesothelioma cells, lung cancer cells or even, sarcoma cells. To help with diagnosis, scientists are trying to find a tumour marker for mesothelioma. A tumour marker is a chemical given off by cancer cells that can be found in the blood and picked up in a blood test. If a definite tumour marker could be discovered for mesothelioma this would be of great benefit for doctors in making more accurate diagnosis of this disease and may also be helpful to monitor the success of treatment. An Australian paper, published in The Lancet in November 2003, is about this search. The researchers were looking into tests for proteins related to mesothelioma. This is early research, but they have had promising results. In their study, 84% of people with mesothelioma tested positive, compared to 2% with other cancers or other lung disease. In a group of people who had been exposed to asbestos but did not have mesothelioma, 7 out of 40 tested positive. 3 of these 7 developed mesothelioma and another got lung cancer within 5 years of the positive test. None of the 33 people who tested negative got mesothelioma within the 8 years following the study. It may be that researchers can build on this work to develop a test for screening for mesothelioma and tests for monitoring the disease in people who already have it.

Chemotherapy
It has been a major challenge for doctors to find chemotherapy drugs that work well in treating malignant mesothelioma. Many trials have been done using epirubicin, doxorubicin, cisplatin and methotrexate, but no standard treatment has been set. This has led researchers to look at newer chemotherapy drugs in combination with some already tried.