Oral Bacteria Associated with Pancreatic Cancer Risk

Individuals who had high levels of antibodies for infectious oral bacteria have twice the risk for developing a fatal form of neoplastic malignancy.

There appears to be a significant association between antibodies for multiple oral bacteria and the risk of pancreatic cancer, adding support for the emerging idea that the ostensibly distant medical conditions are related.

Scientists at Brown University (Providence, RI, USA) conducted a prospective controlled study using medical records and preserved blood samples from a massive dataset of more than 500,000 adults in 10 countries. Detailed health histories and blood samples are available from more than 380,000 of the participants. From that population, the researchers found 405 people who developed pancreatic cancer, but no other cancer, and who had blood samples available. They also selected 416 demographically similar people who did not develop pancreatic cancer for comparison.

The scientists blinded themselves to which samples came from cancer patients and which did not during their analysis of the blood, which consisted of measuring antibody concentrations for 25 pathogenic and commensal oral bacteria. The presence of antibodies in the plasma samples against a preselected panel of whole-cell formalin fixed bacterial antigen was tested using an immunoblot array.

In their study design and analysis, they controlled for smoking, diabetes, body mass index, and other risk factors. They found that high antibody levels for one of the more infectious periodontal bacterium strains of Porphyromonas gingivalis were associated with a two-fold risk for pancreatic cancer. Meanwhile, study subjects with high levels of antibodies for some kinds of harmless commensal oral bacteria were associated with a 45% lower risk of pancreatic cancer.

The authors speculated that the association of high levels of antibodies for commensal bacteria and pancreatic cancer might indicate an innate, highly active immune response that is protective against cancer. They wrote, "Genetic determinants of immune surveillance clearly play a critical role in pancreatic cancer development. Consequently, 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 study was published on September 18, 2102, in the journal Gut.

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