Review for 10.1186/s12876-020-01498-3 (2020)

Reviewer’s report
Title: 
Distinct clinicopathological differences between early gastric cardiac and
non-cardiac carcinomas: A single-center retrospective study of 329 radical
resection cases
Version: 
0 
Date: 
04 May 2020
Reviewer: 
Jan Bornschein
Reviewer's report:
The authors present an overview on clinicopathological features of early gastric
cancers of different location. There are some concerns regarding the relevance of
the data included in this analysis. I don't think all conclusions are well supported
and am not sure how much this paper adds to the body of literature on this topic
(including the authors' own publications). 
Please see further comments below. 
- I personally prefer the separation in "junctional" and "non-junctional" tumours
and would appreciate stratification of junctional tumours according to the
Siewert classification (Siewert & Stein, Br j 
Surg 1998). 
- How exactly was presence of Barrett's oesophagus been defined? Have
endoscopy reports been reviewed. Simple assessment of adjacent IM is not
appropriate to judge on presence of Barrett's. I also don't agree with the
definition of the gastro-oesophageal junction given in this paper. You need to
distinguish between the squamo-columnar junction defining the epithelial
transition and the anatomical GOJ, that is usually defined by the top end of the
gastric folds. 
- H. pylori features in several paragraphs throughout the paper. Judging on H.
pylori status by histology on the resection specimen alone is not appropriate and
leads to an underestimation of the actual infection rate. 
- I don't think that the available literature on this topic is well reflected here.
There are numerous articles that are not cited. I would also have like to see
"Integrated Genomic Characterization of Oesophageal Carcinoma", Nature 2017
by the TCGA being included in the discussion. 
- In the "Background paragraph" you refer to different "cell types" in the
respective compartments of the stomach, but you don't pick this up further,
neither in the results, nor in the discussion section.
- Figure 1 and 2 look nice, but don't add any value to the paper. 
- The tables are crowded, not easy to read (particularly table 2) and should be
revised. Focus on the main items should be considered. 
Labelling of the columns
(e.g. Table 1) is also confusing with different subgroup allocation. This also
raises questions regarding the statistical analysis. Have the results been corrected
for multiple comparison? This is not mentioned in the statistics paragraph. The
authors should also be more specific, on which of the tests has been applied for
which comparison, instead of just listing a range of tests. 
- Although there are no major issues, further language editing by a native
English speaker is advised.
Are the methods appropriate and well described?
If not, please specify what is required in your comments to the authors.
No
Does the work include the necessary controls?
If not, please specify which controls are required in your comments to the
authors.
Yes
Are the conclusions drawn adequately supported by the data shown?
If not, please explain in your comments to the authors.
No
Are you able to assess any statistics in the manuscript or would you
recommend an additional statistical review?
If an additional statistical review is recommended, please specify what aspects
require further assessment in your comments to the editors.
I am able to assess the statistics
Quality of written English
Please indicate the quality of language in the manuscript:
Needs some language corrections before being published
Declaration of competing interests
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1
. 
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salary from an organisation that may in any way gain or lose financially
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or in the future?
3
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Do you hold or are you currently applying for any patents relating to the
content of the manuscript?
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organization that holds or has applied for patents relating to the content of
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paper?
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