Microbial dynamics with CRC progression: a study of the mucosal microbiota at multiple sites in cancers, adenomatous polyps, and healthy controlsOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study investigated the mucosal microbiota at multiple biopsy sites across the spectrum of colorectal cancer (CRC) progression. Researchers used Illumina Miseq sequencing of the 16S rRNA V4 region to profile microbial composition and dynamics in biopsy samples. They also used MinION nanopore sequencing of Fusobacterium-specific amplicons to characterize tumor-associated Fusobacterium nucleatum at the species and subspecies level. The goal was to map how microbial communities shift as tissue progresses from healthy to adenomatous polyp to cancer.
Who was studied?
The abstract describes three groups of biopsy patients from Norway: cancer patients, patients with adenomatous polyps, and healthy controls. Biopsy samples from these groups were sequenced and compared to identify microbiota alterations associated with CRC progression. Fusobacterium-positive tumor biopsies were further subjected to targeted nanopore sequencing. Exact sample sizes for each group are not given in the abstract.
What were the most important findings?
Cancer patients showed enrichment of oral biofilm-associated bacteria compared to adenomatous polyp and control patients, including Fusobacterium, Gemella, Parvimonas, Granulicatella, Leptotrichia, Peptostreptococcus, Campylobacter, Selenomonas, Porphyromonas, and Prevotella. Cancer-associated samples also showed higher abundance of amplicon sequence variants classified as Phascolarctobacterium, Bacteroides vulgatus, Bacteroides plebeius, Bacteroides eggerthii, Tyzzerella, Desulfovibrio, Frisingicoccus, and Eubacterium among others. The presence of Desulfovibrio, a sulfate-reducing bacterial genus capable of producing hydrogen sulfide, was notably elevated alongside these oral pathobionts in cancer tissue. The study further characterized Fusobacterium subspecies within Fusobacterium-positive tumor biopsies using nanopore sequencing.
What are the greatest implications of this study?
These findings support a model in which oral biofilm-associated bacteria, together with sulfate-reducing organisms like Desulfovibrio, colonize and accumulate in colorectal tissue as it progresses toward malignancy. Mapping these site-specific microbial shifts across polyp and cancer stages could help identify microbial markers of CRC progression. Characterizing Fusobacterium at the subspecies level may also refine understanding of which strains are most relevant to tumorigenesis. Together, this work strengthens the rationale for using mucosal microbiota profiles, including sulfide-producing taxa, as part of CRC risk assessment.