Background/Objectives: Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide. Emerging evidence highlights the role of the gut microbiota in the development and progression of CRC. Microbial dysbiosis is hypothesized to contribute to chronic inflammation through a variety of mechanisms, such as the production of free radicals, which induce mutagenesis and immune dysregulation in the host, ultimately leading to diseases such as cancer. Methods: Tumor tissue samples or healthy mucosa tissue were collected for bacterial DNA extraction. The V3–V4 region of the 16S rRNA gene was amplified and sequenced using the Illumina MiSeq platform. Bioinformatics analysis was performed with QIIME2, including quality control, DADA2 denoising, alpha and beta diversity calculation, and taxonomic classification using the SILVA database. Results: Differences in microbial composition were observed between groups. The healthy controls exhibited high relative abundances of beneficial genera such as Faecalibacterium, Bacteroides, and Asteroleplasma, whereas the patients with CRC showed enrichment of atypical genera including Novosphingobium, Bradyrhizobium, and Undibacterium. Alpha diversity was lower in the CRC group, and clear clustering by group was observed in the beta diversity analysis. LEfSe analysis identified potential bacterial biomarkers associated with CRC at both the species and genus levels. Conclusions: The findings of this study support the hypothesis that colorectal cancer is associated with distinct alterations in gut microbiota composition, such as an increase in the Novosphingobium genus and a decrease in the Bacteroides genus. An exploratory description of these microbial profiles may aid in the development of microbiome-based diagnostic and therapeutic strategies and contribute to current knowledge of the role of the gut microbiota in CRC in southern Peru.
Mamani-Ruelas et al. (2026) studied this question.