People with high levels of antibodies to bacteria linked to periodontal disease have an increased risk for pancreatic cancer, while the risk is reduced in those with increased antibodies to oral commensal bacteria, say researchers.
Dominique Michaud, from Brown University in Providence, Rhode Island, USA, and colleagues suggest: "Host genetic susceptibility related to immune function could explain our observations," noting that it "has been proposed that the prolonged inflammation observed in chronic pancreatitis patients is what initiates or aids the progression of a pancreatic tumour."
Conversely, they argue in Gut, the association between a reduced risk for pancreatic cancer and high levels of antibodies to commensal bacteria indicates that "it is plausible that elevated levels of antibodies to oral bacteria in individuals serve as a marker for a genetically stronger immune response, providing protection against carcinogenesis."
The team measured immunoglobulin G antibodies to 25 oral bacteria in prediagnosis blood samples from 405 pancreatic cancer patients and 416 matched controls from the European Prospective Investigation into Cancer and Nutrition Study.
The researchers found that there were very high correlations between pancreatic cancer and antibodies against two strains of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and two species of Veilonella.
Highs levels of antibodies, defined as greater than 200 ng/mL, to the ATTC 53978 strain of P. gingivalis were significantly more common in cases than in controls.
Further analysis indicated that high levels of antibodies to P. gingivalis ATTC 53978 were associated with a significant increase in pancreatic cancer, at a multivariate adjusted odds ratio of 2.14 compared with antibody levels below 200 ng/mL. The association remained significant after taking into account smoking status and removing patients with diabetes from the analysis.
By contrast, the results demonstrated that individuals with consistently high levels of commensal bacteria antibodies had a strong and statistically significant reduced risk for developing pancreatic cancer compared with those with lower antibody levels, at a multivariate adjusted odds ratio of 0.55.
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