Review for 10.1186/s12876-025-03664-x (2025)

Title: Global prevalence of Fusobacterium nucleatum and Bacteroides fragilis in patients with
colorectal cancer: an overview of case reports/case series and meta-analysis of prevalence
studies
Version: 1 Date: 14 Nov 2024
Reviewer's report:
Thanks for the opportunity to look at this manuscript titled “Global prevalence of Fusobacterium
nucleatum and Bacteroides fragilis in patients with colorectal cancer: a systematic review and
meta-analysis”, which demonstrates the prevalence of F. nucleatum and B. fragilis in colorectal
cancer. My comments are as follows:
A. Abstract: The authors should use ‘prevalence’ rather than prevalence frequency.
B. Introduction: The authors should include the SRs of Gethings-Behncke et al 2020
(Fusobacterium nucleatum in the Colorectum and Its Association with Cancer Risk and Survival:
A Systematic Review and Meta-analysis) towards the last part of the introduction. Unfortunately,
there has not been any SRs regarding Bacteroides fragilis (to the best of my knowledge) - and
I suppose this should be the authors’ major evidence gap.
C. Methods:
1. The author contribution section reads “FS, PA, and MP conducted the data extraction”.
However, MP was not included in the main text under data extraction methodology section.
Please, could the authors correct this oversight.
2a. Pls mention the name of these two researchers in section 2.4
2b. The authors should clearly describe their outcomes of interest (primary and secondary) in this
meta-analysis. If we are primarily interested in prevalence estimation (as mentioned in section
2.2), am not sure why we really need the case reports/case series at all? Please explain???
3. The potential confounding effect of (fibre-rich) diet as well as chemo-resistance to CRC is
worth mentioning. And if not considered in the primary studies, should be added as part of the
limitations.
4. In section 2.5, the authors should provide details of the unit in which the effect sizes will be
reported, with their corresponding 95% confidence intervals. Also, explain how the degree of
heterogeneity will be graded and what will constitute substantial heterogeneity.
D. Results
1. The authors should please correct the oversight in line 6-8 of section 3.2. I suppose you want
to say …Almost all of ….. in figure 2 (not figure 3A)….. Furthermore, figure 2 (not figure 4).
Figure 4 is a funnel plot often used to assess publication bias (not heterogeneity).
2. In light of (1) above, the authors should explain the difference between figure 3 and 4. They
have different footnotes too - pls correct as appropriate.
3. In section 3.2, pls correct the 2nd to the last sentence to read ‘studies’ not study
E. Discussion (pls restructure as follows):
1. Paragraph 1 should give a brief summary of your overall findings. The opening statements
from lines 1-4 is OK to start paragraph 1. However, line 5 is appropriate to start the next
paragraph.
2. Line 10 (of the present 2nd paragraph) should start a stand alone ‘3rd’ paragraph.
3. The last 7 lines (of the present 2nd paragraph) should be a stand alone ‘4th’ paragraph for
the limitation section.
4. Regarding the limitation section, the authors should address the potential factors responsible
for the high heterogeneity seen in this meta-analysis. Additional statements on future directions
will be helpful e.g. other bacteria (like panimonas micra and Gemella morbillorum) and their
role in CRC pathogenesis.
5. The authors should please add ‘in’ in line 6 of the conclusion section - Rephrase to read …..
prevalence of these bacteria ‘in’ CRC patients…..
Best wishes,
Dr Ralph Udeh