A new study finds significant associations 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.
Possible clue to a hard-to-diagnose cancer
Human pancreatic tumor cells stained and magnified 400 times. Research suggests a strong link, possibly predictive, between pancreatic cancer and levels of antibodies to certain oral bacteria.
Credit: Dr. Lance Liotta Laboratory/NCI Visuals
The study of blood samples from more than 800 European adults, published in the journal Gut, 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-percent lower risk of pancreatic cancer.
“The relative increase in risk from smoking is not much bigger than two,” said Brown University epidemiologist Dominique Michaud, the paper’s corresponding author. “If this is a real effect size of two, then potential impact of this finding is really significant.”
Pancreatic cancer, which is difficult to detect and kills most patients within six months of diagnosis, is responsible for 40,000 deaths a year in the United States.
Several researchers, including Michaud, have found previous links between periodontal disease and pancreatic cancer. The Gut paper is the first study to test whether antibodies for oral bacteria are indicators of pancreatic cancer risk and the first study to associate the immune response to commensal bacteria with pancreatic cancer risk. The physiological mechanism linking oral bacteria and pancreatic cancer remains unknown, but the study strengthens the suggestion that there is one.
“This is not an established risk factor,” said Michaud, who is also co-lead author with Jacques Izard, of the Forsyth Institute and Harvard University. “But I feel more confident that there is something going on. It’s something we need to understand better.”
Izard, a microbiologist, said the importance of bacteria in cancer is growing. “The impact of immune defense against both commensals and pathogenic bacteria undeniably plays a role,” he said. “We need to further investigate the importance of bacteria in pancreatic cancer beyond the associated risk.”
Prospective, controlled study
To conduct their research, Michaud and Izard drew on medical records and preserved blood samples collected by the Imperial College-led European Prospective Investigation into Cancer and Nutrition Study, 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. The researchers also selected 416 demographically similar people who did not develop pancreatic cancer for comparison.
The researchers blinded themselves to which samples came from cancer patients and which didn’t during their analysis of the blood, which consisted of measuring antibody concentrations for 25 pathogenic and commensal oral bacteria. In their study design and analysis they controlled for smoking, diabetes, body mass index, and other risk factors.
An important element of the study design was that date of the blood samples preceded the diagnosis of pancreatic cancer by as much as a decade, meaning that the significant difference in antibody levels were likely not a result of cancer.
Instead, the underlying mechanisms that link Porphyromonas gingivalis to pancreatic cancer could be causal, Michaud said, although much more research is needed to understand this association.
Meanwhile, the researchers speculate, the association of high levels of antibodies for commensal bacteria and pancreatic cancer, may indicate an innate, highly active immune response that is protective against cancer.
“Genetic determinants of immune surveillance clearly play a critical role in pancreatic cancer development,” the authors wrote. “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.”
Michaud, who studies cancer risk factors generally, continues to investigate the association between oral bacteria and pancreatic cancer in collaboration with Izard.
The National Cancer Institute was the primary funder of the study.
Editors: Brown University has a fiber link television studio available for domestic and international live and taped interviews, and maintains an ISDN line for radio interviews. For more information, call (401) 863-2476.
David Orenstein | EurekAlert!
22.02.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau
Separate brain systems cooperate during learning, study finds
22.02.2018 | Brown University
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
22.02.2018 | Life Sciences
22.02.2018 | Physics and Astronomy
22.02.2018 | Earth Sciences