Microbiota profile is different for early and invasive colorectal cancer and is consistent throughout the colon.

Background And Aim: Microbiota have been associated with several diseases including colorectal cancer (CRC). This study aimed to evaluate the microbiota in early/invasive CRC utilizing stool and cytological brushes to determine differences in relative abundance (RA).

Methods: Colonoscopy patients referred for endoscopic submucosal dissection or previous to CRC surgery were prospectively enrolled. Stool was collected pre-bowel preparation; and brush samples were taken during colonoscopy (three regions). DNA extraction, 16S rRNA next generation sequencing, and biostatistics (qiime and stamp software packages) followed. Primary outcome was the difference in RA of the Fusobacterium genus between the groups. Secondary outcomes included analyses of other microbiota.

Results: Twenty-five patients were included, of which 14 had invasive cancer (≥ 1000 mm into the submucosa). The three major genera for invasive cancer were Bacterioides, Oribacterium, and Fusobacterium, whereas for early cancer were Oribacterium, Bacterioides, and Prevotella (decreasing order of RA). There was a significantly higher RA of Fusobacterium in the invasive cancer group (9.65% vs 0.95%, respectively, P < 0.001). The RA of all genera was similar throughout the colon. In addition to Fusobacterium, the genera Corynebacterium, Enterococcus, Neisseria, Porphyromonas, and Sclegelella showed statistically higher RA in the invasive cancer group. Conversely, the genera Oribacterium, Desulfovibrio, Clostridiales, and Lactobacillus showed lower RA in the invasive cancer group.

Conclusions: The RA of Fusobacterium is higher with invasive CRC than in early CRC patients. In addition, five other bacteria genera were found to be increased, and four decreased in invasive CRC patients. The microbiota per patient was similar throughout the colon.