Page 144 - Ebook-Book JCMS 2025

Microbiota Diversity and Composition in Gastric Cancer by
Gastric Mucosal Brushing: A Cross-sectional Case-control
Study
Thanrada Vimonsuntirungsri1, Chatpol Samuthpongtorn2, Pisit Tangkijvanich3, Rapat Pittayanon1*
1 Division of Gastroenterology, Department of Medicine, Faculty of Medicine, Chulalongkorn University and
King Chulalongkorn Memorial Hospital
2 Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial
Hospital
3 Department of Biochemistry, Faculty of Medicine, Chulalongkorn University
*Corresponding Author E-mail: rapat125@gmail.com
Background: Abstract
The dysbiosis of the gastric microbiota has been implicated in gastric carcinogenesis.
However, previous studies showed a large heterogeneity of the gastric microbiota profiles
in various sampling methods which impacted the diagnostic yield. Currently, the specific
method for assessing non-Helicobacter pylori microbiota associated with gastric cancer
(GC) remain unidentified. This study aimed to compare the diagnostic yield of mucosal
brushing and conventional biopsy sampling methods to identify gastric microbiota in
patients with GC and controls.
Methods: This study, conducted from February 2024 to January 2025, included patients with
treatment-naive GC and asymptomatic controls with normal esophagogastroduodenoscopy
findings. Paired brushing and biopsy specimens from the non-tumoral area located at
gastric body were analyzed using 16S rRNA sequencing of V1-V2 region. Microbiome
analysis accessed α-diversity(Richness and Shannon index) and β-diversity(Bray-Curtis
dissimilarity) between sampling methods and between GC and control groups. The
microbial associations with GC were evaluated with generalized linear mixed models,
adjusted for age and sex.
Results: Fifty samples were analyzed(14 of GC and 36 of controls). When comparing sampling
methods, overall brushing samples showed significantly higher α-diversity than biopsy
(genus richness 80±44 VS 26±17, p< 0.0001; Shannon index 3.70±0.59 VS 2.83±0.77,
p<0.0001). The β-diversity of bacterial genera was also significantly different in over-
all brushing and biopsy samples (PERMANOVA R2 = 0.086, p=0.001). In brush
sampling analysis, the GC group had significantly depleted genus richness and Shannon
index than controls 60±23.5 VS 84.5±45, p=0.03 and 3.35±0.28 VS 3.84±0.50, p=0.008)
but the overall β-diversity did not differ (p=0.07). Sixteen genera exhibited significant
differences in abundance between the GC and control groups.
142 Joint Conference in Medical Sciences 2025