Researcher Says Virus Linked to Mesothelioma

November 16, 2006 - Top cancer researcher, Dr. Michele Carbone of the University of Hawaii, says he and his colleagues are progressing towards deciphering why some people with prolonged exposure to asbestos develop mesothelioma and others with similar exposure do not.

Carbone, who heads the University’s Thoracic Oncology Program, says “it's not just a case of good vs. bad luck, but a combination of the mineral fibers and viruses that's responsible.”  Carbone told the Honolulu Star Bulletin that those factors work together to cause malignant mesothelioma, an aggressive cancer which attacks the membranes lining the chest and abdominal cavities.

People who work in shipyards have high incidence of mesothelioma, meaning 5 percent of those with more than 10 years' exposure will die of cancer, Carbone said. "That's a lot, but it also tells you 95 percent of them equally loaded with asbestos do not get it. So the issue is, why?”  He and his team believe that deciphering the “why” might help to treat those who do indeed develop the disease.

In a paper Carbone submitted to the Proceedings of the National Academy of Sciences journal, he states his reasoning and promotes a link between asbestos fibers and a monkey virus called SV40. 

The paper states that his team of researchers administered SV40 and asbestos to human mesothelial cells in tissue culture and to live hamsters to test the idea that the two are co-carcinogens. “Low amounts of asbestos believed insufficient to cause mesothelioma will cause the disease more often among humans infected with the virus,” the researchers reported.

Carbone noted that his team had previously discovered the monkey virus in some human mesotheliomas, but said he was surprised to find that the virus and asbestos cooperate to cause human cancer.

How did some humans develop a rare monkey virus?  Carbone explains that monkey cells were used in polio vaccine in the U.S. from 1954 to 1962.  Some of the vaccine was infected with the SV40 virus.  Other countries, including the former Soviet Union, were still using the infected vaccine into the late 1970s.

Mesothelioma cells, explained Carbone, harbor the virus better than other cells. "In the presence of asbestos, transformation of human cells increased 10 times or more. What it shows is if you are infected with the virus and also exposed to asbestos, probably your risk to the disease is much higher."

More specific drugs could be developed for mesothelioma if the mechanism were understood, Carbone said.

Carbone, who came to Hawaii earlier this year from Loyola University Medical Center in Chicago, heads the largest team of mesothelioma researchers in the country and boasts one of the largest grants for the study of this disease.