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 2.82, > 0.05) and a lower value on the Simpson index (0.050 0.060, > 0.05). Significant differences in beta diversity were observed at the genus ( = 0.002) and species levels ( = 0.001). , , , and were the dominant phyla. The genera and were found more frequently in colorectal cancer, while and were more frequently found in non-colorectal cancer. The relative abundance of and species was significantly elevated in patients with colorectal cancer. Meanwhile, and 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).