Oral microbiota: risk modulator for pancreatic cancer

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The analysis of the oral microbiota of participants in two large prospective oncological studies helped identify bacterial strains that are associated or not to the risk of developing pancreatic cancer.

 

Poor oral hygiene and a history of gingival disorders have been associated with an increased risk of developing pancreatic cancer. However, the causal relations remain largely unknown. This gray area led an American team to focus on potential relations between oral microbiota (over 700 types of bacteria) and pancreatic cancer. In this study, saliva samples from 361 patients and 371 healthy volunteers (controls) from two large American cohort studies were analyzed*.

A bacterial impact was confirmed

The composition of the oral microbiota was determined  through 16S RNA sequencing in order to assess the correlation between the type of microorganism  and the risk of pancreatic cancer. The researchers were then able to identify bacterial populations with opposing effects. Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, two oral pathogens frequently found in cases of periodontal diseases, are associated with a higher risk of pancreatic cancer. On the contrary, high levels of bacteria from the phylum Fusobacteria  and especially from its genus Leptotrichia were associated with decreased pancreatic cancer risk. The team then ruled out any possible relation between concentration of bacteria under study and smoking status or alcohol consumption, two well-known risk factors. Similarly, it excluded the possible influence of the pancreatic cancer itself on the oral microbiota, by removing all cases that developed within 2 years of sample collection

Non-invasive biomarkers

The now established link between oral microbiota and pancreatic cancer is a step forward in the management of the disease, especially thanks to a better understanding of its etiology. P. gingivalis and A. actinomycetemcomitans, which were associated with an increased risk of pancreatic cancer, could also be used as non-invasive biomarkers of the disease. According to the researchers, this predictive approach should be coupled with good oral hygiene, reduced tobacco consumption or even weigh loss.

 

*Cancer Prevention Study II (American Cancer Society), Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (National Cancer Institute).

 

Sources:

Fan X, et al. : Human oral microbiome and prospective risk for pancreatic cancer: a population-based nested case-control study, Gut 2017;67:120–127. doi:10.1136/gutjnl-2016-312580.