Pancreatic cancer (PC) is an invasive malignancy with a poor prognosis. The 5-year survival rate is only about 10%, primarily due to the absence of a specific early diagnostic indicator and the late stage at which the disease is detected. Among its subtypes, pancreatic ductal adenocarcinoma (PDAC) is the most lethal form of PC. PDAC is currently the third leading cause of cancer-related deaths in the U.S. The risk factors are obesity, diabetes, chronic pancreatitis, smoking, alcohol consumption, and diet. Evidence shows that alterations in oral and gut microbiota communities can stimulate chronic inflammation and enhance PC pathogenesis with specific pathogens like Granulicatella adiacens and Fusobacterium nucleatum enriched in PC, and protective taxa like Bifidobacterium bifidum, Neisseria elongata, and Roseburia intestinalis appear decreased.
This study aimed to evaluate and compare oral and gut microbiota abundance in PC patients and healthy individuals. In addition, it sought to assess the discriminatory potential of microbiota and clinical biomarkers in PC detection.
Twenty newly diagnosed untreated PC patients aged 20 to 70 years old were enrolled from Taleghani Hospital and matched with 20 healthy individuals going for routine check-ups. Lifestyle, comprehensive demographic, dietary, paraclinical, and clinical data were collected by structured interviews, questionnaires, and oral examinations. Saliva and stool samples were collected, and microbial DNA was extracted using Qiagen and Omega Bio-tek kits. Real-time quantitative PCR (qPCR) targeting 16S rRNA regions of G. adiacens, N. elongata, F. nucleatum, B. bifidum, and R. intestinalis was performed with SYBR Green chemistry with a standard curve using Escherichia coli reference DNA.
Statistical analyses were conducted in R with vegan, ggpubr, tidyverse, OptimalCutpoints, and rstatix with means ± standard deviation (SD) or medians with interquartile ranges (IQR). Mann-Whitney U tests or independent t-tests were used for continuous variables, PCA to visualize microbiota clustering, and Fisher’s exact test for categorical variables. Logistic regression with the area under the accuracy (ACC) and curve (AUC) metrics evaluated discriminatory performance with significance set at P < 0.05.
Hematological analysis indicated that patients with PC exhibited significantly reduced red blood cell (RBC) counts (median: 4.08), hemoglobin levels (11.30), and hematocrit (35.05) compared to controls (P < 0.002). Liver enzyme levels were significantly elevated in PC patients, including aspartate aminotransferase (AST: 62.00), alanine aminotransferase (ALT: 40.00), alkaline phosphatase (ALP: 412.50), total bilirubin (1.72), and direct bilirubin (1.05), all significantly higher than controls (P < 0.001). Microbiome profiling revealed increased levels of oral G. adiacens (7.35 log10 CFU/mL) and fecal F. nucleatum (4.37 log10 CFU/g) in PC patients as compared to controls (P < 0.001). Conversely, salivary N. elongata (2.37) and fecal R. intestinalis (2.34) and B. bifidum (3.45) were reduced (P < 0.001).
PCA analysis demonstrated distinct microbial clustering with F. nucleatum and G. adiacens associated with PC, and N. elongata and others were aligned with controls. Logistic regression identified age, hemoglobin, hematocrit, and R. intestinalis as having perfect discriminatory power (AUC = 1.00), with N. elongata showing strong predictive ability (AUC = 0.97), and B. bifidum demonstrating moderate discrimination.
This study showed marked alteration in oral and gut microbiota in PC patients caused by enrichment of pathogenic bacteria and depletion of beneficial species. This highlights distinct microbial signatures that can serve as non-invasive biomarkers for early detection of PC. The results underscore the potential of microbiota-based screening tools and support further research.
Reference: Tavanaeian S, Feizabadi MM, Falsafi S, et al. Oral and fecal microbiome alterations in pancreatic cancer: insights into potential diagnostic biomarkers. BMC Microbiol. 2025;25:624. doi:10.1186/s12866-025-04344-2
