Oral Bacteria Linked With Pancreatic Cancer

Researchers have identified two species of bacteria linked with periodontal disease in healthy individuals that are associated with a risk of developing pancreatic cancer, according to a study (abstract 4350) presented at the 2016 American Association for Cancer Research (AACR) Annual Meeting, held April 16–20 in New Orleans.

“We found that Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, two species of bacteria linked to periodontal disease, were associated with a more than 50% increased risk of pancreatic cancer,” said Jiyoung Ahn, PhD, associate professor of population health and associate director of population sciences at the Laura and Isaac Perlmutter Cancer Center at NYU Langone Medical Center in New York, in a press release. “These data do not show a causal relationship, but they are the first steps in understanding a potential new risk factor for pancreatic cancer, which is vital if we are to develop new approaches for pancreatic cancer prevention and early detection in the future.”

Prior studies have linked a history of periodontal disease and circulating antibodies to selected oral pathogens to increased risk for pancreatic cancer, but no study has looked directly at the presence of oral microbes and the risk for cancer.

This study included 361 patients with pancreatic cancer and 371 matched controls taken from the Cancer Prevention Study II and the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Using prediagnostic oral wash samples, the researchers characterized the composition of the oral microbiota using bacterial 16S rRNA gene amplification and sequencing.

The presence of Porphyromonas gingivalis was associated with a 59% increased risk for pancreatic cancer (odds ratio [OR], 1.59 [95% CI, 1.15–2.20]), and Aggregatibacter actinomycetemcomitans was associated with a 119% increased risk for pancreatic cancer (OR, 2.19 [95% CI, 1.15–4.15]).

Risk remained even after excluding samples from people who developed pancreatic cancer within 2 years of collection of their oral wash samples, which increased the research team’s confidence in the associations that were identified, according to Ahn.

A major limitation of the study was that the population studied was not very diverse-it was predominantly non-Hispanic white and healthy-so the results might not be generalizable to the whole population.