Review for 10.1186/s12876-018-0855-2 (2018)

Reviewer ’s report  
Title: Propensity score -matching analysis to compare clinical ou tcomes of endoscopic 
submucosal dissection for early gastric cancer in the postoperative and non -operative stomachs  
 
Version: 0 Date: 13 Jun 2018  
 
Reviewer: Masaaki Kobayashi  
 
Reviewer's report:  
This report represents that ESD could be selected as the treatment for EGC even in the 
postoperative stomach if careful attention is focused on lesions on the suture line. Although this 
report is interesting, concerns were raised with regard to the followi ng major issues.  
 
1. Although ESD -P is a time -consuming procedure and requires advanced techniques, ESD -P 
achieved high rates of curative resection with a low rate of adverse events. These results had 
reported already in many papers. The authors should sho w the novelty in this study, besides 
exception of potential confounding biases using a propensity score -matching analysis.  
  
2. The primary outcome was procedure time. Operator skill level may be the major factor for 
this study. There were 28 experts and 1 3 trainees between January 1, 2004, and July 31, 
2016. The authors should consider learning curve of 41 operators in the 12 years. ESD -P 
involved suture line (n=19) were performed by selected special experts or every experts?  
 
3. The treatment of ESD for EGC in an anastomotic site requires advanced techniques 
compared with ESD for EGC involving suture line in remnant stomach. The authors should 
separate anastomotic site from suture line.  
 
4. The types of previous gastrectomy performed for lesions in the po stoperative stomach 
included 27 distal gastrectomies, 5 proximal gastrectomies, 1 pylorus preserving 
gastrectomy, and 8 esophagectomies (page 12). However, Table 4 revealed previous surgery 
type was composed of 8 gastrectomies and 33 esophagectomies. Pleas e verify number of 
each type of previous surgery.  
 
5. I wonder the operators performed ESD -P using multiple kinds of endo -knife compared with 
ESD -N. The authors had better evaluate cost effectiveness between ESD -P and ESD -N.  
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
Yes 
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 adequa tely supported by the data shown?  
If not, please explain in your comments to the authors.  
Yes 
Are you able to assess any statistics in the manus cript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommende d, please speci fy what aspects require further 
assessment in your comments to the editors.  
I recommend additional statist ical review  
Quality of written English  
Please indicate the quality of language in the manuscript:  
Acceptable  
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, f ees, funding, or salary from an 
organisation that may in a ny way gain or lose financial ly from the publication of this 
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2. Do you hold any stocks or shares in an organisation t hat may in any way gain or lose 
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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.  
 
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