Gum disease can more than double a person's risk of pancreatic cancer, a Harvard study shows.

In addition, people with a history of gum disease, plus recent tooth loss, have a 2.7-fold higher risk of this fatal cancer than people without gum disease or tooth loss.

Previous studies have linked gum disease to pancreatic cancer. But those studies could not control for smoking, which contributes to both gum disease and cancer.

That was not a problem for Dominique S. Michaud, ScD, and colleagues at Harvard School of Public Health. The researchers analyzed data from 51,529 male health professionals -- a large number of whom were nonsmokers -- who were followed for 16 years.

Michaud's team found that, overall, study subjects who reported gum disease were 64 percent more likely to have pancreatic cancer.

Among nonsmokers, those with gum disease were more than twice as likely to have pancreatic cancer.

The worse the gum disease, the higher the risk. Tooth loss greatly increased cancer risk for the men with periodontal, or gum, disease.

It is not clear why gum disease is linked to cancer risk.

Michaud and colleagues suggest that long-standing gum infections trigger a body-wide immune response: inflammation. Inflamed tissues give off chemical signals that promote tumor growth.

The findings appear in the Jan. 17 issue of the Journal of the National Cancer Institute.

By Daniel J. DeNoon, reviewed by Louise Chang, MD

SOURCES: Michaud, D. Jan 17, 2007; vol 99: pp 171-175.