Colorectal microbiota after removal of 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 asked whether the colonic microbiome returns to normal after surgical removal of colorectal cancer, or stays abnormal. Researchers profiled colonic biopsies using 16S rRNA gene amplicon sequencing of the V3-V4 region. They compared four groups: patients after CRC resection, controls, patients with newly diagnosed CRC, and patients with polyps. Analyses included beta diversity, differential abundance by linear regression and ANCOMBC, co-abundance group clustering, and links between microbiota, diet, and medication.
Who was studied?
The cohort was adults recruited in Cork, Ireland, from 2017 to 2019. It included 63 patients after CRC resection during surveillance endoscopy, compared with 52 to 58 controls, 93 patients with newly diagnosed CRC, and 28 with polyps. Post-resection patients had a mean age of 64.5 years and were 58.7 percent male. Two biopsies were taken per patient, proximal and distal to the anastomosis. Findings were validated against published fecal datasets from France, Canada, the United States, and Japan, using dietary questionnaires for lifestyle data.
What were the most important findings?
The colonic microbiota stayed significantly different from controls in 65 percent of post-resection patients. Clustering split them into two groups: one CRC-like (41 subjects) and one normal-like (22 subjects, about 35 percent). The normal-like group had significantly higher Shannon diversity (p less than 0.0001). Post-resection microbiomes had fewer CRC-associated pathobionts (Fusobacterium, Parvimonas) and more beneficial fiber-fermenting genera. Seven cross-study markers, including Fusobacterium, Parvimonas, Peptostreptococcus, and Porphyromonas, tracked the same split. Higher intake of cruciferous vegetables, fruiting vegetables, peanuts, vegetable soup, and cardiovascular drugs co-varied with the normal-like microbiome.
What are the greatest implications of this study?
The results suggest the microbiome could serve as a risk marker, not just a diagnostic one, identifying which CRC survivors carry a cancer-like microbiota and may warrant closer surveillance. Because diet and cardiovascular drugs co-varied with a more normal microbiome, the authors raise the possibility that lifestyle factors modulate microbiome recovery after surgery. This is correlational, not proven cause. The study was cross-sectional with modest size and variable time since surgery. The authors call for longitudinal studies, ideally with structured dietary intervention, before clinical application.