Oral Microbiota Alterations and Potential Salivary Biomarkers in Colorectal Cancer: A Next-Generation Sequencing StudyOriginal 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 pilot study compared the oral (salivary) microbiome of colorectal cancer (CRC) patients with healthy controls to find compositional differences and candidate diagnostic biomarkers. Saliva was profiled by full-length 16S rRNA gene sequencing (V1-V9) on the Oxford Nanopore long-read platform, aiming for species-level resolution. Analyses in QIIME2 covered alpha and beta diversity, principal coordinate analysis, and LEfSe biomarker discovery, with reads rarefied to 10,000 per sample.
Who was studied?
The cohort was 14 newly diagnosed, untreated CRC patients and 14 healthy controls who screened negative for CRC, recruited in Turkey between March and December 2023. Each group had 7 women and 7 men. Mean age was 58.36 years for CRC patients and 58 years for controls. Saliva samples were collected before any cancer treatment began, then stored at minus 80 degrees until sequencing.
What were the most important findings?
Alpha diversity did not differ (Shannon p equals 0.78), but beta diversity separated the groups by Bray-Curtis PCoA (p equals 0.003), indicating qualitative not quantitative shifts. One bacterial phylum absent in all controls appeared significantly in CRC patients (p equals 0.038), with parallel enrichment at family, genus and species levels. LEfSe identified eight species with LDA score above 2 as candidate biomarkers. The authors highlight pro-carcinogenic oral taxa such as Fusobacterium in this context.
What are the greatest implications of this study?
The findings suggest CRC is linked to a restructured salivary microbiome rather than reduced diversity, supporting saliva as a possible non-invasive screening source. Taxa detected only in patients could serve as early biomarkers, and parallel stool changes in the same participants hint at systemic dysbiosis. This is a small single-center pilot without a validation cohort, and diet, smoking and oral hygiene were not fully controlled. The associations do not establish that these microbes cause cancer.