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