Review for 10.1186/s12876-021-01700-0 (2021)

Reviewer’s report
Title: 
Clinical outcomes of early gastric cardiac cancer treated with endoscopic
submucosal dissection in patients with different indications
Version: 
1 
Date: 
17 Jun 2020
Reviewer's report:
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I have read this manuscript with interest. The author studied the short-term and
long-term outcomes of ESD for EGCC in many patients. However, there are
many results in the whole, and it is difficult to understand because it is long.
Please focus on the points and describe the results and discussion. For example,
regarding the short-term outcomes of EGCC's ESD, many researchers have
already reported in the past, so it is not so important. On the other hand, there are
few reports on long-term outcomes, so I think it is valuable data.
In this study, there were 4 disease-related deaths in long-term outcomes, 1 in the
AI group and 3 in the BEI group. The 4 patients are listed in Table 5, but there
are some uncertainties in their clinical course.
The AI group patient died of metastatic recurrence, but the tumor size was 9mm,
the depth was M3 and the lateral margin was positive. Was the pathological
result of the lesion after ESD for this patient correctly diagnosed? In such cases,
the depth of invasion and the lymph-vascular invasion might sometimes change
due to reexamination, so it is necessary to review the pathological results. Also,
the pathological result of the patient is positive of lateral margin, but did you
consider re-ESD? The patient refuses surgery, but when did the patient refuse to
do it? 
One patient of three BEI groups died from postoperative bleeding. Is this a
related death due to surgical procedures? In this study, 42 people in the BEI
group have undergone surgery, Surgery-related death is 2.4% (1/42). Is this
frequency higher than past reports? If 2.4% is common, I think it is not necessary
to recommend the additional surgery to the elderly patient.
What about this point?
In another BEI group death, a woman in her 40's died of metastasis without
surgery for 5mm SM2 cancer. Why didn't she receive surgery? In this study, the
BEI group had significantly lower survival rates than the other groups. We have
to actively recommend surgery for such cases. The author should mention the
point in the discussion part.

Are the methods appropriate and well described?
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No
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No
Are the conclusions drawn adequately supported by the data shown?
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No
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recommend an additional statistical review?
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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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