THURSDAY, May 23 (HealthDay News) -- People who suffer from frequent heartburn may be at increased risk for cancers of the throat and vocal cords even if they don't smoke or drink alcohol, a new study says.

Interestingly, common over-the-counter antacids seemed to protect against these cancers while prescription medications such as Prilosec, Nexium and Prevacid didn't, the researchers said.

"There has been a controversy about whether heartburn contributes to cancers of the larynx or pharynx," said lead researcher Scott Langevin, a postdoctoral research fellow at Brown University in Providence, R.I.

"And we found out that it does elevate the risk of these cancers. There is about a 78 percent increase in the risk for cancer in people who experience heavy heartburn," he said. "This is important in figuring out who to monitor more closely."

The other finding, which Langevin called "surprising," was the protective effect of common antacids in reducing the risk of cancer.

"We didn't see that protective effect with prescription medications. But it should be noted that people who take them are those who get the worst heartburn, so we shouldn't read too much into that," he said.

Langevin added that it's hard to explain that medication finding, and other studies will be needed to see if it's really the case. "It's possible that these drugs didn't have that protective effect because these were the worst cases of heartburn," he said.

The report was published May 23 in the journal Cancer Epidemiology, Biomarkers & Prevention. And while it uncovered an association between heartburn and cancer of the throat and vocal cords, it didn't prove a cause-and-effect relationship.

Dr. Len Lichtenfeld, deputy chief medical officer at the American Cancer Society, said "the study shows that reflux is associated with an increased incidence of cancers of the larynx and pharynx."

Lichtenfeld said the role of antacids in reducing the risk of cancer needs more study. "Researchers need to determine why antacids work and, more importantly, whether antacids make a difference in also reducing cancer of the esophagus," he said.