Review for 10.1186/s12876-022-02250-9 (2022)

Reviewer’s report
Title: 
Simultaneous or staged resection for synchronous liver metastasis and
primary rectal cancer: a propensity score matching analysis
Version: 
1 
Date: 
04 Mar 2022
Reviewer's report:
The authors present a series of 70 patients with rectal cancer and synchronous
liver metastases (SLM), comparing the outcomes of patients undergoing
simultaneous resection to those undergoing staged resection, either rectum first
or liver first, after propensity score matching (PSM). After PSM, 22 patients who
received a simultaneous resection were compared with 22 patients who
underwent a staged resection. The number of patients is relatively small,
however the series includes only patients bearing rectal cancer.
The authors conclude that simultaneous resection of primary rectal cancer and
SLM is safe and feasible with no difference in survival. The observation that
patients in the simultaneous group experienced significantly fewer recurrences
deserves further study, considering the limited number of patients and limitations
of retrospective studies. However, this study further confirms what has been
suggested by other recent series on the feasibility and safety of simultaneous
resection of rectal cancer with SLM.
The manuscript is well thought out and well written. The discussion is
exhaustive. 
Comments: 
1) In the BACKGROUND, the authors state that "Only one prospective
randomized clinical trial compared these two strategies but only 38 % of
included patients had rectal cancer", but there is no reference. 
2) In the RESULTS, the authors should clearly state that after PSM 22 patients
were in the simultaneous group and 22 in the staged group. 
3) In the DISCUSSION the authors state "Primary colonic cancers do not always
need neoadjuvant treatment before resection, which is impossible in case of
SLMs". Please explain. 
4) I would suggest a revision of the English language to make some passages of
the text clearer.
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Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
Yes
Are the methods sufficiently described to allow the study to be repeated?
Yes
Is the use of statistics and treatment of uncertainties appropriate?
Yes
Is the presentation of the work clear?
Yes
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes