Oral bacteria, fungi linked to pancreatic cancer

Oral microbiota, including bacteria and fungi, have emerged as risk factors for pancreatic cancer development in a recent study.

Researchers used data from two epidemiological cohorts: the American Cancer Society Cancer Prevention Study-II Nutrition Cohort and the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.

Whole-genome shotgun sequencing and internal transcribed spacer (ITS) sequencing were performed to characterize the oral bacterial and fungal microbiome, respectively. Logistic regression was applied to evaluate the association of periodontal pathogens of the red complex (Treponema denticola, Porphyromonas gingivalis, and Tannerella forsythia) and orange complex (Fusobacterium nucleatum, F periodonticum, Prevotella intermedia, P nigrescens, Parvimonas micra, Eubacterium nodatum, Campylobacter shower, and C gracilis) with pancreatic cancer. Microbial risk scores (MRS) for pancreatic cancer were calculated from the risk-associated bacterial and fungal species.

The analysis included 890 participants (mean age 67.2 years, 53.3 percent male), of which 445 received a diagnosis of pancreatic cancer over a median follow-up of 8.8 years. Patients with pancreatic cancer were matched with 445 no-cancer controls based on cohort, 5-year age band, sex, race and ethnicity, and time since oral sample collection.

Three oral bacterial periodontal pathogens—P. gingivalis, E. nodatum, and P. micra—showed a significant association with increased pancreatic cancer risk. A bacteriome-wide scan found eight oral bacteria that seemed to be protective and 13 oral bacteria that were linked to a risk increase (false discovery rate–adjusted Q statistic <0.05).

Of the fungi, greater oral abundance of the genus Candida was associated with an increased risk of pancreatic cancer.

Each standard deviation-increase in MRS, which was based on 27 risk-associated oral species, correlated with more than threefold increase in the odds of pancreatic cancer (adjusted odds ratio, 3.44, 95 percent confidence interval, 2.63–4.51).

These findings point to the potential of using oral microbiota as biomarkers to identify individuals at high risk of pancreatic cancer.