Table 2 Summary of the main results of the included studies
From: Role of the intestinal microbiome in colorectal cancer surgery outcomes
Authors, year | Bacteria1 | Bacterial characteristics in tissues | Association between microbiota composition and tumor stage | Results |
|---|---|---|---|---|
Short-term outcomes | ||||
Van Praagh et al., 2017 | Lachnospiraceae Bacteroidaceae | High abundance + Low microbial diversity in patients with or without C-seal | Not reported | - AL patients without a C-seal showed a significant lower microbial diversity, more Bacteroides, more Lachnospiraceae, and less Prevotella and Streptococci than C-seal patients who developed AL. - AL cases of non-C-seal patients seem to be almost without exception dominated by Lachnospiraceae and Bacteroidaceae with correspondingly low microbial diversity scores - Relation between the composition of the intestinal microbiota and the subsequent development of AL after stapled colorectal anastomoses, but only in patients who underwent surgery without the additional C-seal that covered the anastomoses |
Long-term outcomes | ||||
Flanagan et al., 2014 | F. nucleatum | High vs. low or fold increase from normal | No significant differences between patients with no/low or high F. nucleatum, in TNM/Dukes staging. | - A significant difference in survival between patients without detected F. nucleatum in tumor tissue or low fold increase vs. those with high fold increase. - Median survival of subjects with high F. nucleatum fold increase is 2 years, whereas all subjects with low tumor to normal ratio survive more than 3 years (HR = 19.96, 95% CI = 1.42–281.42, p = 0.0266). |
Flemer et al., 2018 | Pathogen CAG Prevotella CAG Bacteroides CAG Firmicutes CAG | Relative abundance | Not specified | - Pathogen CAG-type microbiota was associated with longer survival (HR = 0.8, CI = 0.6–1.06; p = 0.12) - Prevotella CAG-type microbiota was associated with longer survival (HR = 0.36, CI = 0.12–1.1; p = 0.075). - Bacteroidetes CAG was associated with longer survival (HR = 0.75, CI = 0.58–1.03; p = 0.078). - Firmicutes CAG 2 was associated with shorter survival (HR = 1.52, CI = 0.84–2.75; p = 0.17) |
Kosumi et al., 2018 | Bifidobacterium | Negative vs. low vs. high DNA weight | Difference in Bifidobacteria was not associated with disease stage | No significant associations of the amount of Bifidobacteria with colorectal cancer-specific mortality or overall mortality |
Mima et al., 2016 | F. nucleatum | High vs. low vs. negative DNA load | The amount of tissue F. NUCLEATUM DNA was associated with higher pT stage (p = 0.0007). The association was not statistically significant with pN or M stage. | - Compared with F. nucleatum-negative cases, F. nucleatum-high cases had an HR = 1.58 (95% CI = 1.04–2.39) for cancer-specific mortality - A higher amount of tissue F. nucleatum DNA was associated with shorter colorectal cancer-specific survival (p = 0.023) but no difference in overall mortality rate |
Wei et al., 2016 | B. fragilis F. nucleatum F. prausnitzii | High vs. low abundance | - High abundance of F. nucleatum was significantly correlated with positive lymph node metastasis - High abundance of F. prausnitzii and F. nucleatum was significantly correlated with worse depth of invasion | - Higher level of B. fragilis (9.75% vs. 2.62%, FDR = 0.017) in non-survival group than in survival group, - F. prausnitzii (2.96% vs. 0.92%, FDR = 0.028) and Methylobacterium suomiense (1.91% vs. 0.78%, FDR = 0.098) were more abundant in the survival group. - F. nucleatum was higher in non-survival group than survival group (5.66% vs. 1.08%, FDR = 0.076) and it exhibited a greater abundance in the recurrence group than in survival group (5.10% vs. 1.08%, FDR = 0.08) - B. fragilis and F. prausnitzii might be correlated with patient’s survival in CRC - 3-year OS was significantly lower in patients with high B. fragilis and F. nucleatum than in those with low abundance of these two microbiota (p = 0.001, p = 0.003). - Low abundance of F. prausnitzii showed worse 3-year OS, (p = 0.06). - B. fragilis (HR = 2.01; 95% CI = 1.02–3.96; p = 0.044) and F. nucleatum (HR = 1.99; 95% CI = 1.02–3.87; p = 0.042) were independent predictor of the 3-year OS - B. fragilis (HR = 2.04; 95% CI = 1.11–3.73; p = 0.021) and F. nucleatum (HR = 1.82; 95% CI = 1–3.34; p = 0.05) were associated with poor 3-year DFS both |
Yan et al., 2017 | F. nucleatum | High vs. low level | - In both stage III and IV tumor, F. nucleatum level was significantly higher in CRC tissues than in adjacent normal tissues - F. nucleatum was found to significantly associated with tumor invasion (p = 0.015), LNM status (p = 0.008), and distant metastasis (p = 0.020). - Stage IIIA patients with low F. nucleatum level had no better CSS and DFS than those with high F. nucleatum level - High F. nucleatum level was significantly associated with worse CSS and DFS in stage IIIB and IV patients | - Patients with high F. nucleatum level had a significantly worse CSS and DFS than those with low F. nucleatum level For CSS: HR = 2.22; 95% CI = 1.48–3.32; p < 0.001 For DFS: HR = 2.0; 95% CI = 1.39–2.86; p < 0.001 |
Yu et al., 2017 | F. nucleatum | High vs. low amount | The amount of F. nucleatum was positively associated with the AJCC stage and tumor size | - The 5-year RFS was substantially shorter in the F. nucleatum-high group than the F. nucleatum-low group. - F. nucleatum was an independent predictor of CRC aggressiveness with significant HR for predicting clinical outcome. Its predictive value was comparable with that of the AJCC stage |