Mesothelima Cases Likely Underreported Worldwide

The study is the first to provide a global estimate of unreported mesothelioma cases based on the collective experience of countries with available data on asbestos use and the disease.

For every four to five reported cases of mesothelioma worldwide, at least one case goes unreported, according to a study in the journal Environmental Health Perspectives. This study is the first to provide a global estimate of unreported mesothelioma cases based on the collective experience of countries with available data on asbestos use and the disease.
Malignant mesothelioma is caused almost exclusively by exposure to asbestos. The disease is difficult to diagnose until it is far advanced, and the prognosis is usually poor. The study’s authors used numbers of mesothelioma deaths as a proxy for numbers of cases, because mesothelioma patients usually die shortly after diagnosis. Also, in many countries, deaths in general tend to be more uniformly and accurately reported than diagnoses.
The authors assessed the relationship between country-level asbestos use from 1920 through 1970 and mesothelioma deaths reported between 1994 and 2008. Cumulative asbestos use in 89 countries, which accounted for more than 82 percent of the global population in the year 2000, totaled more than 65 million metric tons during 1920–1970. The United States, Russia, United Kingdom, Germany, and Japan led the group in asbestos use, defined as production plus import minus export. For the 56 countries also reporting mesothelioma data, there were approximately 174,300 such deaths during 1994–2008.

Mesothelioma typically develops 20–50 years after exposure to asbestos. Accordingly, a country’s cumulative use of asbestos in prior decades was found to clearly and reliably predict numbers of recent mesothelioma deaths in the countries reporting mortality data. When the authors extrapolated this finding to the 33 countries not reporting mesothelioma data, they estimated 38,900 additional cases may have occurred in these countries during that same 15-year period.

“Our most important finding is the magnitude of unreported mesothelioma in countries that use asbestos at substantial levels but report no cases of the disease,” says study co-author Ken Takahashi of the University of Occupational and Environmental Health in Japan. Such countries include Russia, Kazakstan, China, and India, which rank in the top 15 countries for cumulative asbestos use.
Takahashi says any country that uses asbestos is certain to have cases of mesothelioma. He notes the study’s estimates may be conservative because both asbestos use and mesothelioma may be underreported in the countries used as the basis for their estimates.
The authors propose that every country ban the mining, use, and export of asbestos because, Takahashi says, mesothelioma can be prevented by eliminating exposure to asbestos. They also propose that developed countries share experience and technology to help developing countries better diagnose, report, and manage mesothelioma cases.

Proteins May Hold Key to Mesothelioma Susceptibility

Altered cellular proteins may reveal clues as to why some people exposed to asbestos get mesothelioma, while others don’t. That is the conclusion of new research conducted in China.

Asbestos has long been known to cause mesothelioma, but the mechanisms by which it does so remain largely a mystery. For instance, scientists have been at a loss to say why some people can work around asbestos for years with no ill effects, while others with the same level of exposure contract malignant mesothelioma. Understanding why this happens may not only help predict who is at higher risk, but may also give doctors new targets for treatments.

Now, research from China is shedding new light on the subject. The researchers focused their attention on cellular proteins, the command ‘signals’ that direct most cellular activity. To conduct the study, the team looked at samples of three kinds of cells: healthy mesothelial cells, healthy mesothelial cells that were exposed to crocidolite asbestos in the lab, and malignant mesothelioma cells. A multiplex immunoblot-based assay test was used to measure the expression levels of 112 different proteins and phosphoproteins in each of the samples.

The levels of 16 proteins and phosophoproteins were altered (7 were decreased, 9 were increased) in the benign mesothelial cells after they were treated with crocidolite asbestos in the lab. Most of the effected proteins were those that involve DNA damage repair and cell cycle regulation. In the malignant mesothelioma cells, 21 proteins were found to be altered (5 were decreased, 16 were increased). The researchers report “substantial overlap” between the proteins affected in the asbestos-treated cell and the mesothelioma cells.

Reporting in the international medical journal Mutation Research, the Chinese scientists conclude that asbestos exposure “has extensive affects on regulatory pathways and networks” and that these altered proteins may be used in the future to indentify people who are at high risk for developing mesothelioma. Medical treatments that target the levels of these key proteins might also be a way to control mesothelioma, which is notoriously difficult to treat with standard therapeutic modalities.
Sources:
Wang, H et al, “Crocidolite asbestos-induced signal pathway dysregulation in mesothelioma cells”, May 6, 2011, Mutation Research. Epub ahead of print.

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