Review for 10.1186/s12876-020-01543-1 (2020)

Reviewer’s report
Title: 
Severe weight loss after minimally invasive oesophagectomy is associated
with poor 5-year survival in patients with oesophageal cancer
Version: 
2 
Date: 
29 Jul 2020
Reviewer's report:
"PEER REVIEWER ASSESSMENTS: 
OBJECTIVE - Full research articles: is there a clear objective that addresses one
or several testable research questions? (Brief or other article types: is there a
clear objective?)
Yes - there is a clear objective
DESIGN - Is the current approach (including controls and analysis protocols)
appropriate for the objective?
No - there are minor issues
EXECUTION - Are the experiments and analyses performed with sufficient
technical rigor to allow confidence in the results?
Yes - experiments and analyses were performed appropriately
STATISTICS - Is the use of statistics in the manuscript appropriate?
Not sure - I am not able to assess the statistics in this study
INTERPRETATION - Is the current interpretation/discussion of the results
reasonable and not overstated?
No - there are minor issues
OVERALL MANUSCRIPT POTENTIAL - Has the author addressed your
concerns sufficiently for you to now recommend the work as a technically sound
contribution? If not, can further revisions be made to make the work technically
sound?
Probably - with minor revisions
PEER REVIEWER COMMENTS: 
GENERAL COMMENTS: * Have the authors responded adequately to each of
the questions or concerns you raised in your comments?
Yes
* Have they also made changes to reflect their responses in the manuscript
itself?
Yes
* What is your overall impression of the revised manuscript?
It is improved by the revisions, but some issues remain.
REQUESTED REVISIONS: 
Design 
- minor issues. 
These have now been addressed in the limitations section
of the manuscript (Discussion).
Interpretation 
- minor issues
These relate to some revisions in the Discussion. 
Further revision of this section
would provide additional clarity about further research.
ADDITIONAL REQUESTS/SUGGESTIONS: 
There is still some uncertainty in that the authors state that "FT was likely placed
in patients with deep tumour invasion who underwent preoperative therapy.". 
If
the reasons for FT placement are not fully understood, this should be explored in
the Discussion and proposed as future research question to determine the effects
of FT placement on weight loss and survival. 
'Categorised' could be used in the text in some places in addition to 
'organised',
to improve the readability of the manuscript.
This section in the Discussion is new, and improves this section, however soe
further clarity is needed. 
"Previous studies reported that 10% weight loss was
associated with poor prognosis after
oesophagectomy ………………….no-FT group would be
needed."
Major - now that the cut-off for severe weight loss if clearer I am concerned that
in fact all of the patient in this study had severe weight loss post opertaively.
Most studies would categorise 10% weight loss as sever, so I think this may be a
reason why the patients in 
this study did quite badly - they were ALL severely
underweight. 
I cannot see an explanation for using this cut off, please provide it.
Because all the patients had severe weight loss, it would be more difficult to see
a difference between the FT and non FT groups. 
This might be an issue for
discussion.
Could I suggest: 
In this study, 60% of the patients experienced >10% weight loss. No
significant differences were found between these two groups. - This sentence
needs further discussion 
- this is a different finding from previous research and
no explanations are offered in the paper.
For the FT group, (median duration of FT placement 78
days) we *did* not demonstrate improvement of postoperative weight loss,
although some studies report that FT can improve nutritional status (how long
were these FT placed?).
It may be that nutritional support via FT might be needed for a longer time after
oesophagectomy. In our study, in the no FT group, we did not give nutritional
support. This might suggest that non FT patients should take an oral nutritional
supplement. Our results suggest that nutritional support for the FT group and no-
FT group would be needed. to reduce post-operative weight loss and improve
outcomes.
The paragraph which follows this would benefit from some minor revision as
there is some repetition."
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Is the study design appropriate to answer the research question (including the use
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presented?
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Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
No