Table 1.
Summary of studies that investigated Fusobacterium nucleatum in saliva and/or colorectal mucosa or stool in colorectal cancer (CRC) cases and controls (C).
| Author -year | Country | No. of CRC cases/C | Exclusion if previous ATB use (period) | Specimen type | Specimen collection time | Collection kits and storage conditions | Bacterial analysis method |
F. nucleatum detection and level quantification outcomes |
|---|---|---|---|---|---|---|---|---|
| Russo et al. 2017 | Italy | 10/10 | Yes (last 3 months) | Unstimulated saliva | 1 day before surgery |
Sterile tube, − 80 °C |
Next generation sequencing & qPCR |
F. nucleatum level: In saliva: No significant difference between CRC cases and C In stool: No significant difference between CRC cases and C Saliva Vs stool: higher abundance in saliva than in stool, in CRC (p < 0.01) and in C (p < 0.002) |
| Stool | ||||||||
|
Fresh tumor mucosa (in CRC cases) |
During surgery | 0.9% NaCl solution, − 80 °C | ||||||
| Guven et al. 2019 | Turkey | 71/77 |
Yes (last 3 months) |
Saliva | Before cancer treatments |
Centrifuge tube, − 20 °C |
qPCR |
F. nucleatum detection: CRC cases: 97.2% Vs C: 96.1%; p > 0.99 F. nucleatum level: (in Log10 copies/ml) CRC cases: 6.89 ± 1.07 Vs C: 6.35 ± 0.78; p = 0.001 |
| Komiya et al. 2019 | Japan |
14/0 (No C) |
Yes (last month) |
Saliva | Before/after colonoscopy | Sterile tubes, anaerobic conditions |
PCR (conventional) |
F. nucleatum detection: Saliva: 100% Tumor mucosa: 57% Saliva and tumor mucosa: 43% (F. nucleatum identical strain in 75% of patients with both saliva and tumor positive to F. nucleatum) |
| Tumor mucosa | During colonoscopy | |||||||
| Kato et al. 2016 | USA | 68 /122 | –- | Oral rinse | –- |
Commercial mouthwash (15% alcohol), − 80 °C |
16SrRNA gene sequencing |
Dominant Phyla: Fusobacteria was not dominant, only 3.7% of all sequences No association between F. nucleatum and CRC |
| Abed et al. 2020 | Israel |
7/0 (No C) |
No: ATB was taken just before surgery |
Saliva | 1 day before surgery, or just after colonoscopy | Sterile tubes, anaerobic conditions | PCR (conventional) |
F. nucleatum detection: Saliva: 100% Tumor mucosa: 100% |
| Tumor mucosa | 45 min after resection | |||||||
|
3/0 (No C) |
Yes (just before surgery) | Saliva | 1 day before surgery, or just after colonoscopy | Sterile tubes, anaerobic conditions | Whole genome sequencing | Great similarity between F. nucleatum strains in saliva and tumor in each subject | ||
| Tumor mucosa | 45 min after resection | |||||||
| Kageyama et al. 2019 | Japan | 24/118 |
Yes (last month) |
Stimulated saliva | Before cancer therapy | Sterile tube, − 80 °C | 16SrRNA gene sequencing |
Differentially abundant OTUs: OTUs corresponding to F. nucleatum were not the most abundant bacteria OTUs in CRC |
| Yang et al. 2019 | USA | 231 / 462 |
Yes (last week) |
Oral rinse | – | Commercial mouthwash, − 80 °C | 16S rRNA gene sequencing |
F. nucleatum detection: CRC cases: 99.6% Vs C: 99.6% (p = 1) |
| Flemer et al. 2017 | Ireland | 99/103 + (32 polyp patients) |
Yes (last month) (ATB during surgery time) |
Oral swabs (45 CRC& 25 C) | – | − 80 °C | 16S rRNA gene amplicon sequencing |
F. nucleatum abundance: Fusobacterium less abundant in oral swabs of CRC cases compared to C |
| Stool | Before colonoscopy | − 80 °C | ||||||
| Colorectal and tumor mucosa | During surgery or colonoscopy | RNA later at 4 °C for 12 h, then at − 20 °C |
No. Number, CRC Colorectal cancer, C Controls, F. nucleatum Fusobacterium nucleatum, ATB Antibiotic, OTU Operational taxonomic unit, – Not reported.