Review for 10.1186/s12876-020-01578-4 (2021)

Reviewer’s report
Title: 
Central lymph node metastasis is predictive of survival in advanced
gastric cancer patients treated with D2 lymphadenectomy
Version: 
0 
Date: 
26 Oct 2020
Reviewer's report:
The purpose of this retrospective review was to determine if positive extra-
regional (D2, or central) lymph nodes were associated with survival. 
The
investigators utilized a large, single institution dataset with approximately a third
having central lymph node involvement.
The authors are correct that there are no published reports evaluating the impact
of central lymph node metastasis for patients treated with upfront gastrectomy.
The methods and statistical analysis is very straightforward.
In the multivariate Cox analysis for DFS, does including CnLN metastasis as
well as pathological N stage diminish the impact of node positivity, as the two
variables are similar?
In the discussion, the authors should discuss if the term CnLN metastases adds
anything to the current Japanese nodal classification system. 
CnLN dissection is
a much more common procedure in the West than formal Japanese D2 lymph
node dissection and nodal classification. It is unclear if the Japanese nodal
classification system is as relevant to Western centers.
Publons Reviewer Recognition
. Springer Nature can send verification of this
review directly to Publons (a subsidiary of Clarivate Analytics). If you would
like to take advantage of this service, please click on the “Yes” option below.
Your name, email address, title of the reviewed manuscript, name of the journal,
and date of your review submission (the “Review Data”) will then be transmitted
to Publons upon publication of the manuscript. If you have already registered at
Publons, they will notify you of the receipt of this review and update your profile
as per your settings and their policy. If you are not registered with Publons, you
will receive an email from them asking you to register in order for them to be
able to recognize your review on your new profile page. Publons may use the
Review Data to generate derivative metadata for the benefit of Publons and you
as a reviewer, carefully considering the sensitivity of such information. For
example, Publons may verify your record as a reviewer by updating your profile
published on its webservice if you have registered for such service or help
editors to identify candidate reviewers. Please find the details of processing in
Publons’ privacy policy 
https://publons.com/about/terms
No
Declaration of competing interests
Please complete a declaration of competing interests, considering the following
questions:
1
. 
Have you in the past five years received reimbursements, fees, funding, or
salary from an organisation that may in any way gain or lose financially
from the publication of this manuscript, either now or in the future?
2
. 
Do you hold any stocks or shares in an organisation that may in any way
gain or lose financially from the publication of this manuscript, either now
or in the future?
3
. 
Do you hold or are you currently applying for any patents relating to the
content of the manuscript?
4
. 
Have you received reimbursements, fees, funding, or salary from an
organization that holds or has applied for patents relating to the content of
the manuscript?
5
. 
Do you have any other financial competing interests?
6
. 
Do you have any non-financial competing interests in relation to this
paper?
If you can answer no to all of the above, write 'I declare that I have no competing
interests' below. If your reply is yes to any, please give details below.
I declare that I have no competing interests
Reviewer Publication Consent.
 I agree for my report to be made available
under an Open Access Creative Commons CC-BY License (
http://creativecommons.org/licenses/by/4.0
) if this manuscript is accepted for
publication. Any comments that I do not wish to be included in the published
report have been included as confidential comments to the editor, which will not
be published.
If you are not happy for us to publish this report, please contact the editorial
office before completing the review.
If you wish, you can include your name in your published report. Please note
you must decide whether to include your name at the start of the process and
confirm this decision whenever prompted. If you change your decision later, we
will not be able to publish your name.
I agree to the terms of the CC-BY 4.0 license; please 
do not
 publish my name
with my report. (default)
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