Gut Microbiome Signatures Along the Colorectal Adenoma-Carcinoma Sequence in a Colombian Cohort: A Stepwise Analysis Starting With Diagnosis
Juliana Victoria Martinez Janne, Mabel Elena Bohorquez, Javier EscobarPURPOSE
Colorectal cancer (CRC) is a leading cause of cancer death in Colombia, where dietary patterns and healthcare access differ from high-income countries. Global evidence links gut dysbiosis to CRC, but few studies come from Latin America. We initiated a stepwise characterization of the gut microbiome in Colombian patients with CRC, adenomatous polyps, and healthy controls. Here we report the first step: comparing microbial composition by diagnosis. Future steps will correlate microbiome with diet/lifestyle and validate findings in an external cohort (n = 100) from Universidad del Bosque.
METHODS
We conducted a nested case-control study in a Bogotá hospital (8 polyps, 5 CRC, 4 healthy controls). Participants completed a validated food-frequency and lifestyle questionnaire (fiber, red/processed meat, fruits/vegetables, alcohol, tobacco, physical activity). Fecal 16S rRNA sequencing (V3-V4) followed by DADA2 (SILVA v138.1) generated Amplicon Sequence Variants (ASVs). Beta diversity was assessed by PCoA on Bray-Curtis distance with PERMANOVA (pairwise FDR-adjusted). Differential abundance used DESeq2 (
RESULTS
Descriptive dietary analysis showed lower fiber and higher processed meat intake in CRC patients versus controls (consistent with known risk factors). Microbiome: no alpha diversity differences (
CONCLUSION
The transition from polyps to CRC in this Colombian cohort is characterized by a massive loss of butyrate-producing and probiotic bacteria together with a selective gain of Ruminococcus. These preliminary microbiome signatures by diagnosis justify the next phases: correlation with dietary patterns and validation in the larger Universidad del Bosque cohort, aiming to develop affordable microbiome-based biomarkers for early CRC detection in low-resource settings.