Link Between Oral Microbiota and Pancreatic Cancer Risk
Introduction to Pancreatic Cancer
Pancreatic cancer ranks as the 12th most common cancer globally and is the 7th leading cause of cancer-related deaths. This cancer exhibits a high lethality, with the five-year survival rate at approximately 24% for early diagnoses and a mere 1.8% for advanced stages. Given its severity, effective prevention strategies are crucial, yet the underlying causes of pancreatic cancer remain poorly understood.
Established Risk Factors
Among the few well-documented risk factors for pancreatic cancer is cigarette smoking. Other modifiable risks include obesity, diabetes, and chronic pancreatitis, often observed in patients diagnosed with this disease. Recent studies have also linked periodontal disease, commonly referred to as gum disease, to an increased risk of developing pancreatic cancer.
The Role of Oral Microbiota
Oral health is significantly influenced by the composition of the oral microbiome, which contains over 700 species of bacteria residing in the human mouth. Distinct microbial ecosystems are associated with conditions such as gingivitis and dental caries. Specific bacteria, including Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, have been identified as contributors to periodontal disease. These findings indicate that alterations in oral microbiota may play a role in the connection between periodontal disease and pancreatic cancer risk.
Research Overview
Study Design and Participants
A comprehensive case-controlled study conducted by researchers from the National Cancer Institute and Tehran University of Medical Sciences examined the oral microbiota of patients diagnosed with pancreatic cancer compared to non-cancerous controls. The study involved 273 pancreatic cancer cases and 285 clinic-based controls recruited from hospitals in Tehran, Iran, between 2011 and 2015. Researchers extracted DNA from saliva samples to analyze the participants’ oral microbial profiles.
Key Findings
The study revealed significant differences in the overall oral microbial communities between the pancreatic cancer cases and the control group. Certain microbial taxa were notably linked to pancreatic cancer presence. Increased levels of Haemophilus were associated with a lower likelihood of pancreatic cancer, whereas higher levels of Enterobacteriaceae, Lachnospiraceae, Bacteroidaceae, and Staphylococcaceae correlated with an elevated risk. Interestingly, while the periodontal pathogen P. gingivalis did not show an association with increased pancreatic cancer risk, A. actinomycetemcomitans was found to contribute to additional risk. These results were published in the journal Cancer Medicine.
Study Limitations
The authors of the study acknowledged several limitations inherent to the case-control design. Since saliva samples were collected at the time of diagnosis, establishing a causal relationship between microbial composition and pancreatic cancer risk proves challenging. It remains unclear whether the observed differences in oral microbiota existed prior to cancer development or emerged following disease onset. Additionally, the control group comprised patients who did not have pancreatic cancer but may have been referred for other conditions that could impact their microbial profiles.
Conclusion and Future Directions
To substantiate these findings, large, prospective cohort studies are necessary. Identifying oral microbiota linked to cancer development could potentially yield predictive biomarkers for the early detection of pancreatic cancer.
Written by Cheryl Xia, HBMSc
References: Vogtmann, E. et al. Oral microbial community composition is associated with pancreatic cancer: A case‐control study in Iran. Cancer Med cam4.2660 (2019) doi:10.1002/cam4.2660. Image by Arek Socha from Pixabay.