Table 2.
Baseline characteristics of studies determining the microbiota of CRC and non-cancerous mucosal tissues.
| First Author, Year | Country | No. Participants (Males) | Age Mean ± SD Median (Range) |
Recruitment | Exclusions | NCT Distance from Tumor |
|---|---|---|---|---|---|---|
| Marchesi, 2011 [19] | The Netherlands | 6 (5) | Mean 63.5 (49–71) | Undergoing CRC surgery | NR | 5–10 cm |
| Chen, 2012 [40] | China | 46 (NR) For analysis: 27 (14) |
Mean 61 (37–81) | Undergoing CRC surgery | Diabetes, infectious diseases, particular diets; use of antibiotics within 1 month of sample collection | Pa2t: 2–5 cm; Pa10t: 10–20 cm |
| Geng, 2013 [45] | China | 8 (4) | Mean 56.9 ± 14.4 | Undergoing CRC screening | NR | NR |
| Zeller, 2014 [56] | Germany | 38 (25) | Mean 61.7 ± 13.5 (34–90) | Undergoing CRC surgery | Previous colon or rectal surgery, CRC, inflammatory or infectious injuries of the intestine; need for emergency colonoscopy | NR |
| Allali, 2015 [37] | USA Spain |
USA: 22 (11) Spain: 23 (15) |
Mean 63.6 (42–88) Mean 69.8 (49–85) |
Tissue bank Undergoing CRC surgery |
NR | USA: NR Spain: 5 cm |
| Burns, 2015 [39] | USA | 44 (12) | Mean 64.9 ± 16.7 (17–91) | Biobank | NR | NR |
| Gao, 2015 [58] | China | 31 (15) For analysis: 20 NCT |
Mean 67 ± 7.2 | Undergoing CRC surgery | Use of antibiotics within 2 months, regular use of NSAIDs, statins, or probiotics; chronic bowel disorders, food allergies/dietary restrictions; pre-operative radiation or chemotherapy | 5 cm |
| Nakatsu, 2015 [59] | China | DC: 52 (31) VC: 50 (26) |
DC: Mean 67.85 ± 13.18 VC: Mean 61.34 ± 9.97 |
Undergoing CRC screening | Personal history of CRC, IBD, prosthetic heart valve or vascular graft surgery; contraindications for colonoscopy | ≥4 cm |
| Brim, 2017 [38] | USA | 10 (5) | Range 41–88 | Undergoing CRC surgery | NR | NR |
| Drewes, 2017 [43] | Malaysia | 23 (12) | Mean 62.22 ± 11.99 | Undergoing CRC surgery | Personal history of CRC or IBD; pre-operative radiation or chemotherapy | NR (as far as possible) |
| Flemer, 2017 [57] | Ireland | 59 (37) | Range 41–90 | Undergoing CRC surgery | Personal history of CRC, IBD, or IBS; use of antibiotics the month prior to surgery | OFFD and OFFP: 2–5 cm; UDD and UDP: 10–30 cm from the tumor |
| Gao, 2017 [44] | China | 65 (35) | Mean 63.49 ± 1.46 | Undergoing CRC surgery | Use of antibiotics or probiotics within 4 weeks, acute diarrhea, adenoma or polyps, IBD, IBS | >5 cm |
| Kinross, 2017 [47] | UK | 18 (10) | Median 76 (55–85) | Undergoing CRC surgery | Previous colorectal surgery, undergoing emergency surgery; pre-operative chemotherapy or radiotherapy; use of antibiotics or probiotics 6 weeks prior to surgery; history of FAP or IBD | 5 cm and 10 cm |
| Cremonesi, 2018 [41] | Germany | 31 (21) For analysis: 27 |
67.5 (35–82) | Undergoing CRC surgery | NR | NR |
| Hale, 2018 [46] | USA | 106 (57) | Mean 65.3 (23–90) | Undergoing CRC surgery | Radio or chemotherapy 2 weeks before enrollment | NR (adjacent and distal) |
| Loke, 2018 [50] | Malaysia | 17 (7) | Mean 62.47 (41–84) | Undergoing CRC surgery | Pre-operative radiation or chemotherapy; history of CRC or IBD | NR |
| Richard, 2018 [60] | Italy | CAC: 7(5) SC: 10 (5) |
CAC: Mean 50.7 ± 10 SC: Mean 68.8 ± 12.1 |
Undergoing CRC surgery | Infectious colitis, coagulation disorders, anti-coagulant therapy; use of antibiotics or antifungal therapy 2 months before inclusion | <5 cm |
| de Carvalho, 2019 [42] | Brazil | 152 (81) For analysis: 15 |
Mean 60.63 ± 13.7 | Undergoing CRC surgery | NR | NR |
| Leung, 2019 [48] | Australia | 19 (9) | Mean 64.7 ± 15.4 | Undergoing CRC surgery | NR | Proximal resection margin |
| Liu, 2019 [49] | China | 8 (5) | Mean 61.3 ± 10.1 (50–78) | Undergoing CRC surgery | NR | 2 cm |
| Saffarian, 2019 [52] | France | 58 (37) | Mean 68.98 (23–92) | Undergoing CRC surgery | Undergoing chemotherapy, radiotherapy, or antibiotic treatment | 15–20 cm |
| Pan, 2020 [51] | China | 23 (11) | Range: 49–70 | Undergoing CRC surgery | Use of antibiotics prior to sample collection | >5 cm |
| Sheng, 2020 [53] | China | 66 (38) | Range: 35–94 | NR | Radiotherapy or chemotherapy before surgery; use of antibiotics, NSAIDs, statins, or probiotics 3 months before surgery; family history of CRC; IBD; diabetes; hypertension; food allergies | >10 cm |
| Wang Q, 2020 [54] | China | 36 (NR) | NR | Undergoing CRC surgery | Use of antibiotics or probiotics 4 weeks before surgery; undergoing radiotherapy or chemotherapy; diabetes; infectious diseases | >5 cm |
| Wang Y, 2020 [61] | China | 75 (48) | Mean 63.4 (29–82) | Undergoing CRC surgery | NR | Adjacent and off tumor |
| Wirth, 2020 [55] | Germany | 6 (NR) | NR | Undergoing CRC surgery | NR | NR |
| Choi, 2021 [62] | Republic of Korea | 51 (51) | Range: 43–86 | Undergoing CRC surgery | NR | NR |
| Liu, 2021 [63] | China | DC: 11 (8) VC: 10 (8) |
DC: Mean 64.91 ± 15.20 VC: Mean 65.33 ± 7.54 |
NR | NR | NR |
| Malik, 2021 [64] | USA | 51 (30) | 62 ± IQR 20 | Undergoing CRC surgery | Hereditary CRC syndromes, IBD; neoadjuvant treatment | NR |
| Nardelli, 2021 [65] | Italy | 20 (10) | Mean 69.4 | Undergoing CRC surgery | IBD or IBS; use of antibiotics, pro/prebiotics, antivirals, or corticosteroids 2 months prior to sample collection | NR |
| Niccolai, 2021 [66] | Italy | 45 (NR) | Range: 30–90 | Undergoing CRC surgery | Previous cancer surgery, chemo or radiotherapy; use of immunosuppressives, antibiotics, or probiotics in the previous 2 months; cancer, IBD | NR |
| Okuda, 2021 [67] | Japan | 29 (15) | Range 37–94 | Underwent CRC surgery | CRC with FAP; IBD | 3 cm |
| Zhang, 2021 [70] | China | 136 (81) For analysis 101 (58) |
Median 64 (21–88) For analysis: Median 64 (21–88) |
Undergoing CRC surgery | No chemo or radiotherapy and no antibiotics 1 month before resection | NR (as far as possible) |
Abbreviations: AM: adjacent mucosa; CAC: colitis-associated colorectal cancer; CRC: colorectal cancer; DC: discovery cohort; FAP: familial adenomatous polyposis; IBD: inflammatory bowel disease; IBS: irritable bowel syndrome; NCT: non-cancerous tissue; NR: not reported; NSAIDs: non-steroidal anti-inflammatory drugs; OFFD: off-distal; OFFP: off-proximal; Pa2t: matched paracancerous tissue 2–5 cm; Pa10t: matched paracancerous tissue 10–20 cm; SC: sporadic colorectal cancer; SD: standard deviation; UDD: undiseased distal; UDP: undiseased proximal; VC: validation cohort.