IDDF2024-ABS-0378 Serial changes in the fecal bacterial gene markers after endoscopic removal of colorectal advanced adenoma: a prospective cohort study

<h3>Background</h3> Emerging data demonstrate the altered gut microbiome is implicated in the development and progression of colorectal neoplasia. A panel of fecal bacteria gene markers (<i>Fusobacterium nucleaum</i>, <i>Fn; Bacteroides clarus</i>, <i>Bc; Clostridium hathewayi</i>, <i>Ch</i>; and <i>Lachnoclostridium</i>, <i>m3</i>) has been identified as a non-invasive biomarker for the detection of colorectal neoplasia and its recurrence. We aimed to determine the serial changes in these markers after the removal of advanced adenoma (AA). <h3>Methods</h3> This is a prospective cohort study conducted in a tertiary hospital in Hong Kong. Consecutive patients who underwent endoscopic removal for AA between 15 December 2021 and 31 December 2023 were screened. Patients with high-quality colonoscopy before or during the procedure and complete removal of adenomas were enrolled. Stool samples at baseline (before procedure), month 1, and month 3 after the procedure were collected. The relative abundances of four bacterial gene markers (<i>Fn</i>, <i>Bc</i>, <i>Ch</i>, and <i>m3</i>) were determined by quantitative PCR (qPCR). Factors associated with the change of bacterial markers were analyzed using Spearman’s correlation analysis. <h3>Results</h3> A total of 154 patients were included in the analysis. The mean age of included patients was 67.7 ± 8.9 years. There were 70 (45.5%), 66 (42.9%), and 18 (11.7%) patients undergoing polypectomy, endoscopic submucosal dissection (ESD), and endoscopic mucosal resection (EMR), respectively. The mean size of lesions was 22.3 ± 13.9 mm. There were 79 (51.3%), 68 (44.2%), and 7 (4.5%) patients with tubular adenoma, tubulovillous/villous adenoma, and sessile serrated adenoma/traditional serrated adenoma, respectively. After the removal of AA, there was no significant serial change in four fecal bacterial gene markers (IDDF2024-ABS-0378 Figure 1). Both the host and lesion characteristics were not associated with the changes in the fecal bacterial gene markers (IDDF2024-ABS-0378 Figure 2). <h3>Conclusions</h3> No significant serial change in the fecal bacterial gene markers was observed after the endoscopic resection of AA, indicating that the hostile microbiota environment persists despite the removal of colorectal neoplasms. Our results suggested the potential role of gut microbiome in the surveillance of colorectal neoplasia and the potential of gut microbiome modulation for preventing its recurrence.