Review for 10.1186/s12876-021-01683-y (2021)

Reviewer’s report
Title: 
Collision of Epstein-Barr virus-positive and -negative gastric cancer, diagnosed by molecular
analysis: A case report
Version: 
0 
Date: 
06 Nov 2020
Reviewer's report:
Summary
This manuscript describes an interesting case of two distinct, but intersecting, gastric tumors. One tumor
is EBV positive and one tumor is EBV negative. 
Major comments
1. It seems strange that H. pylori is not even mentioned, since it is the major cause of gastric cancer. Was
the patient H. pylori positive? An obvious explanation for the two independent tumors is that one was
caused solely by H. pylori, while EBV contributed to the other.
2. It would also be useful to have a brief discussion on what is known about C-MYC and HER2
mutations in gastric cancer, especially regarding associations with EBV or H. pylori.
3. In the legend for figure 2, the word "box" or "boxed area" should be used instead of a square symbol. 
4. S-1 therapy should be defined.
Minor comments
1. The Background exactly repeats sentences in the abstract. It would be better to make the sections more
distinct. 
2. In figure 1, it would be useful to point to gastric landmarks, such as the antrum and/or locations of the
esophageal and duodenal junctions.
3. Resolution of figure 2a could be better.
4. The letters marking panels in figure 3 need to be larger. They are very difficult to read.
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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
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Yes
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Yes
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manipulation?
Yes