Gut microbiome profiles in Chilean participants with colorectal adenomas: an exploratory 16S rRNA sequencing study

Colorectal cancer (CRC) is the third most commonly diagnosed cancer globally and the second leading cause of cancer-related mortality. The disease typically progresses from premalignant adenomatous lesions. Recent studies highlight the pivotal role of the gut microbiota in colorectal carcinogenesis, suggesting a complex interplay between the microbiota and tumor development. This study analyzes gut microbiota profiles in a single-center cohort of Chilean individuals with and without adenomas, using 16S rRNA sequencing to interrogate microbial changes associated with the transition from healthy colon epithelium to precancerous lesions. The results show that the adenoma-associated microbiota is characterized by increased Proteobacteria abundance and decreased Firmicutes abundance compared with healthy controls. Participants with precancerous lesions exhibit increased abundance of Desulfovibrio, a genus of sulfate-reducing bacteria capable of producing hydrogen sulfide (H₂S), a microbial metabolite that has been linked to DNA damage and epithelial stress responses. These findings provide a baseline of the microbial landscape in our population and identify biomarkers associated with premalignant lesions, highlighting microbiome analysis as a diagnostic tool for colorectal disease.