June 15, 2007

VICC joins cancer ‘hot spot’ study

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Reid Thompson, M.D.

VICC joins cancer ‘hot spot’ study

Researchers at the Vanderbilt-Ingram Cancer Center have joined a regional effort to determine why the Southeast is a "hot spot" for deadly brain cancers.

With the help of a five-year, $4.2 million grant awarded by the National Cancer Institute this spring, Vanderbilt-Ingram and four other cancer centers will try to identify genetic and environmental factors that may contribute to the region's relatively high incidence of glioma.

“We're hoping to enroll as many as 1,000 patients,” said the study's principal investigator, Kathleen Egan, M.P.H., Sc.D., of the H. Lee Moffitt Cancer Center & Research Institute in Tampa, Fla. “Ours will be the largest epidemiologic study of this disease conducted in the United States.”

Also participating in the study are the University of Alabama Cancer Center in Birmingham, Emory University Cancer Center in Atlanta, and the Kentuckiana Cancer Institute in Louisville.

Although rare, glioma (also called glioblastoma) is one of the most rapidly fatal of all human cancers, said Reid Thompson, M.D., director of the Vanderbilt Brain Tumor Center, who is participating in the study. “Ninety-five percent of patients don't survive for two years after diagnosis,” he said.

About two years ago, Thompson and Egan, at the time an associate professor of Medicine at Vanderbilt, discovered the “hot spot” on mortality maps prepared by the NCI’s Division of Cancer Epidemiology and Genetics.

Immediately, they decided to try to find out what accounted for it.

“Kathy put together a lengthy questionnaire for patients to fill out,” Thompson said, covering everything from diet to possible job-related exposures to cancer-causing chemicals.

“We're also collecting DNA on these patients,” he said. “We're looking at some genetic polymorphisms” that in other studies are related to cancer risk.

“It is thought that some people are genetically more susceptible to damage caused by smoking and other carcinogens,” explained Egan, who also is professor of Interdisciplinary Oncology at the University of South Florida in Tampa. “We speculate that the same thing may be going on in gliomas.”

One clue to the genetic link: gliomas are more common in men than women and in Caucasians than African-Americans.

“This really makes gliomas stand out,” she said.

One possible risk factor that has been largely ruled out: cell-phone use.

For one thing, Egan said, the maps of glioma mortality have remained remarkably consistent since 1950 — long before cell phones were introduced.

Last month a Chattanooga television station reported that more than 20 cases of glioma have occurred among residents in the Dalton, Ga., area since 1999.

It's too early to tell whether the cluster occurred by chance alone or whether these cases are tied to a common environmental risk factor, Egan said.

That, she added, is what the study is trying to find out.