"We've known for a long time that esophageal adenocarcinoma primarily affects Caucasians and very rarely affects African-Americans," says David G. Beer, Ph.D., the John A. and Carla S. Klein professor of thoracic surgery and professor of radiation oncology at Michigan Medicine.
"We wanted to see if African-Americans have something genetic that's protective. If we understand why people have low risk, that can lead to understanding how to prevent cancer in those at high risk."
About 17,290 Americans will be diagnosed with esophageal cancer this year. Adenocarcinoma represents about two-thirds of cases but is rarely seen in African-Americans.
In the study, published in Gastroenterology, researchers examined tissue samples from African Americans and European Americans, including both those with esophageal adenocarcinoma and those without. They measured gene expression and protein levels and found a difference in the enzyme called GSTT2. This was significantly higher in African-Americans compared to Caucasians.
Researchers found Caucasians have a duplication on a portion of the genome that appears to reduce the expression of GSTT2. This enzyme protects cells against oxidative damage, such as the type caused by reflux, a key risk factor for esophageal adenocarcinoma.