Variation of microbiota depending on the location of colorectal cancer

Abstract

Colorectal cancer (CRC) growth may be determined by various factors, with gut microbiota being one of them. The aim of this study is to Identify the microbiota differences in tumoral tissue (TT), non-tumoral tissue (NTT) and feces depending on CRC localization. Prospective analysis was conducted on patients with CRC who underwent colorectal surgery in 2021 and 2022. Three samples were collected from each patient: feces, tissue from tumor (TT), and tissue from healthy colon (NTT). The study employed 16S rRNA massive sequencing techniques, followed by bioinformatics analyses. A total of 23 patients, comprising 18 males and 5 females, were included in the study. Tumor distribution revealed 12 cases in the right colon, 7 in the left colon, and 4 in the rectum. Significant differences were observed in beta diversity between the microbiota of feces and both types of tissue (TT and NTT). However, no differences in beta diversity were noted between TT and NTT. NTT exhibited a predominance of the phylum Actinobacteriota, while Bacteroidetes was the main phylum in feces. TT was characterized by a higher proportion of Fusobacteriota, with the genera Fusobacteria and Streptococcus being predominant compared to feces and genus Fusobacteria compared to NTT. When considering tumor location, notable differences emerged. There was greater microbiota diversity in the right colon compared to the left colon and rectum. Phyla Clostridiales, Bifidobacteriales, Acidaminococcales, and Vibrionales were more abundant in the right colon, while Staphylococcales were more prevalent in the left colon. The observed variations in microbiota based on tissue type and location imply its potential involvement in colorectal cancer (CRC) pathogenesis.