NASHVILLE, July 22 (UPI) -- U.S. researchers are trying to determine why the South has become the Cancer Belt and why African-Americans experience higher rates of several cancers.

"When you look at a map of brain cancer incidence in the United States the Southeast just lights up in red," Dr. Reid Thompson, of Vanderbilt-Ingram Cancer Center in Nashville said in a statement.

"When we found this hot-spot on the National Cancer Institute's mortality maps we realized something unusual is going on in this region."

Brain cancer is one of the most alarming malignancies disproportionately affecting people who live in this cancer hot-spot, Thompson said.

However, the most prevalent cancer in the South is lung cancer. Southerners continue to smoke more than individuals in other regions of the country, the researchers said.

"We're asking patients about their diets, possible job-related exposure to cancer-causing chemicals, and we're collecting DNA samples," Thompson said. "We know there are some genetic markers that are linked to other forms of cancer and they may play a role in brain cancer, as well."

The Southern Community Cohort Study hopes to recruit 90,000 people in 12 Southern states to learn about their lifestyles, their family medical histories and their risk factors for cancer and other serious diseases.