Americans’ growing girth—and carbohydrate intake—may be partially to blame for rising rates of esophageal cancer, a new study indicates.

The U.S. incidence of esophageal cancer increased from 16.4 to 27.1 million cases—a 65-percent jump—during the period from 1973 to 2001, according to analyses by researchers at Case Western Reserve University and University Hospitals in Cleveland.

During the same period that esophageal cancer rates increased, Americans upped their carb intake by roughly 120 grams a day, according to the National Nutrient Data Bank. And the median obesity rate in the United States almost doubled from 1990 to 2001, indicates U.S. Centers for Disease Control and Prevention data.

Researchers had noted an association between rising rates of type 2 diabetes, obesity, and esophageal cancer, and wanted to figure out whether rising consumption of carbs—particularly “bad” carbs lacking nutritional value—might also be associated with the increase in esophageal cancer. They found a strong correlation between increasing total carbohydrate intake and rising esophageal cancer rates. They also saw a strong link between increasing intake of refined carbohydrates, in the form of corn syrup, and higher esophageal cancer rates. In addition, increasing rates of obesity corresponded with increasing carbohydrate consumption.

However, these findings cannot prove conclusively that increased carb intake causes esophageal cancer, cautions study coauthor Cheryl L. Thompson, PhD, fellow of family medicine at the Case Comprehensive Cancer Center at Case Western Reserve University.

“This is purely a statistical association. You cannot prove causation with this type of study,” Thompson says. “Nonetheless, this provides further evidence for the important role of carbohydrate intake, obesity, and insulin resistance in cancer development.”

This study was published in the Mar. 2008 issue of the American Journal of Gastroenterology.