Table 1.
Details of studies (n = 19) included in the review. CRA: colorectal adenoma; CRC: colorectal carcinoma.
| Reference | Year | Methods for Microbiota Analysis | qPCR | N. of Patients | Samples | Area |
|---|---|---|---|---|---|---|
| Liang et al. | 2020 | Metagenomic sequencing | NA | 35 (adenomatous polyps) | Stool | China |
| Yu et al. | 2019 | 16S rRNA gene sequencing | NA | 20 (CRA) | Stool | China |
| Mangifesta et al. | 2018 | 16S rRNA gene sequencing; qPCR (Fusobacterium nucleatum). |
The deduced cell number was evaluated by comparing the cycle threshold (Ct) values obtained with those from a standard curve. Standard curves were calculated from serial dilutions of a culture with a known cell number (as determined by viable count assessment) for the bacterial strain versus Ct produced for each target gene. Results are expressed as genome copy numbers/gr. |
12 (4 adenomatous polyps, 8 hyperplastic polyps) | Biopsy of Colonic Mucosa with Polyp and Healthy Marginal Tissue | Italy |
| Rezasoltani et al. | 2018 | Absolute qPCR (Streptococcus bovis/gallolyticus, Enterococcus faecalis, Enterotoxigenic Bacteroides fragilis, F. nucleatum, Porphyromonas spp., Lactobacillus spp., Roseburia spp. and Bifidobacterium spp) | The standard curve was plotted, by eight dilution points each tested in duplicate, using DNA obtained from reference strains. Results are expressed as CT. |
118 (31 normal controls, 21 hyperplastic polyp, 16 sessile serrated polyp, 29 tubular adenoma, 21 villous/tubuvillous polyp) |
Stool | Iran |
| Wachsmannova et al. | 2018 | ENTEROtest 24 plus MALDI-TOF mass spectrometry Gentamicin-protection assay to distinguish intracellular bacteria |
NA | 29 (10 CRA, 10 CRC, 9 healthy subjects) | Biopsy samples | Slovakia |
| Sze et al. | 2017 | 16S rRNA gene sequencing | NA | 67 (adenoma, N = 22, advanced adenoma, N = 19, carcinoma, N = 26). | Stool | USA |
| Yoon et al. | 2017 | 16S rRNA gene 454-pyrosequencing |
NA | 24 (healthy control, conventional adenoma, sessile serrated adenoma, CRC, each n = 6) |
Biopsy samples | Korea |
| Lu et al. | 2016 | 16S rRNA gene pyrosequencing | NA | 51 (31 adenoma, 20 healthy volunteers) | Adenoma mucosal biopsy samples and adjacent normal colonic mucosa |
China |
| Park et al. | 2016 | 16S rRNA gene pyrosequencing | NA | 26 (8, tubular adenoma, 10 sessile serrated adenoma/polyp, 8 CRC) | Colorectal mucosal tissue | Korea |
| Goedert et al. | 2015 | 16S rRNA gene sequencing | NA | 61 (24 normal patients, 20 CRA, 2 CRC, 15 with other conditions) | Stool | USA, China |
| Nugent et al. | 2014 | qPCR (Lactobacillus sp., Escherichia coli, Bifidobacterium sp., Clostridium sp., Bacteroide sp., Eubacteria) |
To generate a standard curve, the target 16S rRNA was amplified from a positive control strain by PCR. Results are expressed as Log Transformed Copy Number. |
30 (15 adenoma, 15 adenoma-free control subjects) |
Rectal mucosal biopsies | USA |
| Chen et al. | 2013 | 16S rRNA gene 454-pyrosequencing |
qPCR assays to determine the amounts of total bacteria, Bacteroides genus, and Bifidobacteria spp. A constructed plasmid was chosen to create a 10-log fold standard curve. | 94 (47 sex- and age matched patients with advanced CRA and healthy subjects) |
Stool | China |
| Sanapareddy et al. | 2012 | 16S rRNA gene 454 titanium pyrosequencing |
Abundance of a specific taxon was calculated by the delta–delta threshold cycle (DDCt) method. | 71 (33 subjects with adenomas and 38 subjects without adenomas (controls) |
Mucosal biopsies | USA |
| Shen et al. | 2010 | 16S rRNA gene sequencing | NA | 44 patients (normal colonic mucosa of 21 adenoma and 23 non-adenoma subjects) | Colorectal biopsies | USA |
| Feng et al. | 2015 | Metagenomic sequencing | NA | 147 (57 healthy controls, 44 advanced adenoma, 46 carcinoma) |
Stool | Austria |
| Ito et al. | 2015 | Quantitative PCR for F. nucleatum. | The Ct values for F. nucleatum were normalized to prostaglandin transporter (PGT) comparative analysis of the cycle thresholds (DCt). Results were expressed as 2-ΔΔCt |
465 premalignant lesions (343 serrated lesions and 122 non-serrated adenomas) and 511 CRC | Tumor tissue specimens | Japan |
| Kim et al. | 2020 | 16S rRNA gene sequencing | NA | 240 (patients with advanced adenoma, N = 102), matched controls n = 102), patients with CRC, N = 36) |
Stool | USA |
| Peters et al. | 2016 | 16S rRNA gene sequencing | NA | 540 Conventional adenoma cases (N = 144), serrated polyp cases (N = 73), or polyp-free controls (N = 323). |
Stool |
USA |
| Saito et al. | 2019 | 16S rRNA gene sequencing | NA | 81 (47 CRA, 24 intramucosal colorectal cancer, 10 healthy subjects) | Colonoscopy aspirates | Japan |