Features of the Intestinal and Respiratory Microbiome in Colorectal Cancer Patients in Western Siberia

To perform the first concurrent characterization of gut and respiratory microbiome profiles in colorectal cancer patients from Western Siberia, Russia. We analyzed synchronous fecal and sputum samples from 40 treatment-naive colorectal cancer patients and 45 healthy controls using 16S rRNA gene (V3-V4) sequencing and QIIME 2-based bioinformatic workflows. While alpha-diversity indices did not differ significantly between groups, beta-diversity analysis revealed substantial compositional differences for both ecosystems. Colorectal cancer patients exhibited gut enrichment of Proteobacteria, Fusobacteria, Fusobacterium, Odoribacter, Lachnospiraceae_UCG-010, Erysipelatoclostridium, Parvimonas, Finegoldia, Clostridium and Bacteroides (Bacteroides fragilis), alongside sputum enrichment of phyla Bacteroidetes and Actinobacteria, as well as genera Neisseria, Prevotella, Lactobacillus, Rothia, Nocardia, Leptotrichia, Campylobacter, and Helicobacter. Stage-associated shifts included elevated Akkermansia in gut microbiomes of patients with advanced-stage disease and higher Campylobacter in early-stage sputum. These findings identify distinct gut–respiratory dysbiotic signatures in a previously understudied population. Our results underscore the potential of dual-compartment microbiome profiling for developing non-invasive biomarkers and require validation in larger, multicenter cohorts to elucidate mechanistic links between respiratory dysbiosis and colorectal carcinogenesis.