Asbestos May Not Play Primary Role in Cancer, Study Says

Asbestos alone does not play as much a role in initiating\r\nmesothelioma as previously thought, according to a recent study.

Asbestos alone does not play as much a role in initiating mesothelioma as previously thought, according to a study published in the Aug. 31 issue of the Proceedings of the National Academy of Sciences.

The research, conducted by Dr. Michele Carbone at the Cardinal Bernardin Cancer Center of Loyola University Medical Center in Maywood, Ill., offers preliminary evidence that the virus, Simian virus 40 (SV40), and asbestos fibers work together to transform healthy cells into malignant ones, resulting in mesothelioma, a rare and fatal form of cancer.

"The results provide us with significant new information about the role of environmental contaminants in the development of disease and enhance our understanding of cancer," said Carbone, the study''s principle author and an associate professor of pathology at Loyola University Stritch School of Medicine.

Approximately 2,500 deaths due to mesothelioma occur annually in the United States, but the number of cases is growing, said Carbone. About 80 percent of patients with this form of cancer have had some occupational exposure to asbestos.

Normally, SV40 kills most human cells it enters because it keeps making copies of itself inside the cell until the cell dies, said Carbone. Because the infected cell dies, no cancer can occur.

The study found that although SV40 can make mesothelioma cells in tissue culture malignant, infected mesothelial cells will not automatically become cancerous.

However, the risk of malignancy may increase if cells are exposed to both SV40 and asbestos fibers.

"The transformation process from healthy cell to malignant cell is enhanced through the presence of asbestos fibers," said Carbone. "Asbestos fibers alone are unable to transform the cell, but they seem to promote the cancer-causing work of SV40, thereby increasing the cell''s potential for becoming malignant."

Exactly how asbestos and the virus work together will be the focus of future studies, Carbone said.

"We do know that asbestos suppresses the body''s immune system, and this suppression may play a role in the development of the cancer."

by Virginia Sutcliffe

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