The data doesn't show a cause-and-effect relationship between the bacteria and pancreatic cancer, but it is a first step "in understanding a potential new risk factor," Ahn said. The research was released at the American Association for Cancer Research meeting here in the form of an abstract.
Ahn acknowledged that scientists don't yet know the answer to the big question: If those bacteria are culprits, how, exactly, do they contribute to an increased likelihood of pancreatic cancer? "We don't yet know how oral bacteria affect the pancreas," she said.
Chris Mason, a geneticist at Weill Cornell Medicine, who wasn't involved in the study, agreed that the next step is trying to figure out the mechanism for how oral bacteria might damage the pancreas. Still, he said, the new data, "has important implications for understanding the genesis of cancer and the interaction between human cells and other microbial or viral organisms in or around us."
To do the study, Ahn and her colleagues analyzed oral-wash samples collected over several years as part of two large cancer prevention and screening studies conducted by the National Cancer Institute and the American Cancer Society. Those studies enrolled healthy people and then followed them over years for a variety of outcomes, including the development of cancer. Using genomic technologies, Ahn and her fellow researchers generated profiles of each bacterial species present in the samples.
Ahn said about 1.5 percent of Americans will be diagnosed with pancreatic cancer and that only 5 percent will live for five years or more. If scientists can figure out the role of oral bacteria, she said, it could point to new ways to screen for and possibly prevent the cancer.