Distinct intratumoral microbiome of young-onset and average-onset colorectal cancerOriginal 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 examined the tumor-associated microbiome in colorectal cancer (CRC), comparing young-onset CRC (yoCRC, diagnosed under age 50) to average-onset CRC (aoCRC, diagnosed over age 60). Researchers used 16S rRNA amplicon sequencing on tumor tissue and paired adjacent non-malignant tissue to characterize microbial composition. They applied multiple bioinformatics tools (Phyloseq, microbiomeSeq, metagenomeSeq, and NetComi) alongside statistical tests including PERMANOVA, ANOVA, and Wilcoxon tests to assess differences in microbial diversity and community structure between the two groups.
Who was studied?
The study included fresh frozen tumor and paired adjacent non-malignant tissue specimens prospectively collected from 136 patients with young-onset CRC and 140 patients with average-onset CRC. The yoCRC group was defined as patients diagnosed before age 50, while the aoCRC group consisted of patients diagnosed after age 60. Clinical and tumor characteristics, such as tumor location and stage, were also recorded for both cohorts.
What were the most important findings?
yoCRC tumors were more often left-sided, rectal, and diagnosed at stage IV compared to aoCRC tumors. yoCRC tumors also showed significantly higher microbial alpha diversity and distinct beta diversity patterns relative to aoCRC tumors. Akkermansia and Bacteroides were enriched in yoCRC tumors, whereas aoCRC tumors showed greater relative abundances of Bacillus, Staphylococcus, Listeria, Enterococcus, Pseudomonas, Fusobacterium, and Escherichia/Shigella (the Enterobacteriaceae-associated Escherichia/Shigella group).
What are the greatest implications of this study?
These findings suggest that yoCRC has a distinct intratumoral microbial profile compared to aoCRC, indicating that age of onset may be linked to different microbial dysbiosis patterns in CRC development. The clinical differences in tumor location and stage, paired with microbial differences, imply that yoCRC may represent a biologically distinct disease process rather than simply an earlier-onset version of aoCRC. This raises the possibility that microbiome-informed diagnostics or risk stratification could eventually help address the rising incidence of yoCRC.