Differences in diversity and composition of mucosa-associated colonic microbiota in colorectal cancer and non-colorectal cancer in Indonesia

BACKGROUND Colorectal cancer is the third most common malignancy and the fourth leading cause of cancer-related deaths worldwide. Several studies have shown an association between gut microbiota and colorectal cancer. Gut microbiota is unique and can be influenced by geographic factors and habits. This study aimed to determine the diversity and composition of colonic mucosal microbiota in patients with and without colorectal cancer. AIM To determine the diversity and composition of colonic mucosal microbiota in patients with and without colorectal cancer in Indonesia. METHODS This case-control study included 59 subjects (35 colorectal cancer patients and 24 non-colorectal cancer patients indicated for colonoscopy at Dr. Cipto Mangunkusumo Gastrointestinal Endoscopy Center and Fatmawati Hospital. Microbiota examination was performed using 16S rRNA sequencing. Bioinformatics analysis was performed using the wf-metagenomics pipeline from EPI2Me-Labs (Oxford Nanopore Technologies platform). RESULTS Patients with colorectal cancer had a higher median index value on the Shannon index (3.28 vs 2.82, P > 0.05) and a lower value on the Simpson index (0.050 vs 0.060, P > 0.05). Significant differences in beta diversity were observed at the genus (P = 0.002) and species levels (P = 0.001). Firmicutes , Proteobacteria , Bacteroidetes , and Fusobacteria were the dominant phyla. The genera Bacteroides, Campylobacter, Peptostreptococcus, and Parvimonas were found more frequently in colorectal cancer, while Faecalibacterium, Haemophilus, and Phocaeicola were more frequently found in non-colorectal cancer. The relative abundance of Fusobacterium nucleatum, Bacteroides fragilis, Enterococcus faecalis, Campylobacter hominis, and Enterococcus faecalis species was significantly elevated in patients with colorectal cancer. Meanwhile, Faecalibacterium prausnitzii, Faecalibacterium duncaniae, and Prevotella copri were more commonly found in non-colorectal cancer. CONCLUSION Patients with colorectal cancer exhibit distinct differences in the composition and diversity of their colonic mucosal microbiota compared to those with non-colorectal cancer. This study was reviewed and approved by the Ethics Committee of Faculty of Medicine, Universitas Indonesia (No. KET-1517/UN2.F1/ETIK/PPM.00.02/2023).