Influence of topography on the mucosa-associated gut microbiota in colon cancer

The intestinal microbiota plays a key role in host homeostasis and has been associated with the development of colon cancer (CC). However, most studies overlook the impact of anatomical topography on microbial composition.

To evaluate differences in the microbiota profile between healthy mucosa and tumor tissue in CC patients, comparing results by anatomical location (right vs. left colon).

Cross-sectional observational study including 50 CC patients who underwent surgery at Hospital Virgen del Rocío (Seville, Spain). Paired samples of tumor and healthy mucosal tissue were analyzed using 16S rRNA sequencing via MinION platform and Kraken2 database. Parametric and non-parametric statistical tests were applied.

No significant differences were found in alpha diversity indices (Shannon and Simpson) between right and left colon in either healthy or tumor tissue. In healthy mucosa, the phyla Bacteroidota and Verrucomicrobiota were significantly more abundant in the left colon. In tumor tissue, no statistically significant differences were found; however, the phylum Synergistota showed differences that approached statistical significance (P = .058), with higher abundance in the left colon compared to the right colon.

The microbiota of healthy mucosa differs according to tumor topography, while tumor-associated microbiota appears homogenized regardless of location. These findings suggest that the neoplastic process may standardize the microbial environment. This insight could contribute to future research on topography-specific biomarkers and personalized therapeutic strategies.