Objectives: Human oral microbiota is evaluated in several cancers; however, data on colorectal cancer (CRC) are very limited. Based on this, we aimed to investigate the composition of oral microbiota in CRC and to compare them with healthy controls. Methods: Saliva samples from 32 patients who were diagnosed with CRC and from 32 healthy controls in the same age group were evaluated in this study. Bacterial populations were identified through the multiplication of partial 16S rDNA sequences and comparison with databases after next-generation sequencing (Illumina MiSeq). Results: In family-level examinations, the relative abundance of Pasteurellaceae was decreased and that of Neisseriaceae was increased in patient group (p=0.008 and p=0.036, respectively). The relative abundance of Bacillales showed a negative correlation with disease stage (r=-0.638, p<0.001), while the relative abundance of Proteobacteria showed a positive correlation with the stage of disease (r=0.450, p=0.01). Conclusion: In our study, there were significant differences between the relative abundances of Pasteurellaceae and Neisseriaceae in the saliva of CRC patients. Additionally, the correlation between disease stage and abundance of Bacillales and Proteobacteria members was a novel finding, which needs validation in larger series. These findings might have implications for screening and prognostication of CRC. Keywords: Colorectal cancer, neisseriaceae, next-generation sequencing, oral microbiota, pasteurellaceae
Corresponding Author: Deniz Can Guven