Review for 10.1186/s12876-022-02296-9 (2022)

Title: Sarcopenia Is Associated with Prognosis in Patients with Esophageal Squamous Cell
Cancer after Radiotherapy or Chemoradiotherapy
Version: 3 Date: 02 Mar 2022
Reviewer's report:
"PEER REVIEWER ASSESSMENTS:
OBJECTIVE - Full research articles: is there a clear objective that addresses a testable research
question(s) (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 major issues
EXECUTION - Are the experiments and analyses performed with technical rigor to allow
confidence in the results?
No - there are minor issues
STATISTICS - Is the use of statistics in the manuscript appropriate?
Yes - appropriate statistical analyses have been used in the study
INTERPRETATION - Is the current interpretation/discussion of the results reasonable and not
overstated?
No - there are minor issues
OVERALL MANUSCRIPT POTENTIAL - Is the current version of this work technically
sound? If not, can revisions be made to make the work technically sound?
Maybe - with major revisions
PEER REVIEWER COMMENTS:
GENERAL COMMENTS:
The study tries to determine the prognostic value of sarcopenia on both progression free survival
and overall survival on oesophageal squamous cell cancer patients receiving radiotherapy or
chemoradiotherapy. The study could be a useful addition to the literature on the topic, however
work is needed on the way in which sarcopenia is defined.
Strengths
The study provided useful data on prognosis for survival in oesophageal squamous cell cancer
patients, including a focus on nutritional related variables.
Weaknesses
The study focuses on sarcopenia as a prognostic factor; however, sarcopenia is not evaluated,
only muscle mass. The manuscript needs to be modified to either focus on muscle mass or to
include a full diagnosis of sarcopenia following a suitable method such as that of the Asian
working Group on Sarcopenia.
REQUESTED REVISIONS:
Introduction.
The key rationale for the study is the third paragraph of the introduction in which contradictory
findings in terms of the use of sarcopenia as a prognostic factor for survival in oesophageal
cancer is outlined. This paragraph needs to be improved to make it clearer that this study will
include additional factors…
Methods.
The definition of sarcopenia is based on that reported in a previous study in which skeletal muscle
index was used as the unique criteria to detect sarcopenia. However, diagnosis of sarcopenia
requires a three-step process involving muscle mass, muscle strength and physical performance.
See for instance the Asian Working Group for Sarcopenia 2019 update for a suitable example
for the population in this study (Chen et al., 2020). It seems unlikely that measures of physical
performance and muscle strength are available in this group of patients, which means the article
should not focus on sarcopenia as it has not been diagnosed. It would be better to use muscle
mass instead.
In patient characteristics, how were tobacco and alcohol ‘abuse’ defined?
Results.
The 3-year PFS of the patients is reported to be 32.4% (just before Figure 2), however the 3-
year PFS for both groups (sarcopenia and non-sarcopenia) are both reported to be less than this
value, which can’t be true. The values are clearly different to those shown in Figure 5.
There are many differences in the way result are reported (sometimes with p values, others
without). It is also stated in the methods that any variables with p<0.2 in univariate analyses
would be included in the multivariate models, however this does not appear to be case looking
at the tables. A more detailed description of how variables were chosen for the multivariate
analysis should be provided.
Discussion.
The discussion should not include any results.
The suggestion that a higher percentage of patients had sarcopenia indicates that sarcopenia
might be more sensitive to identify nutritional problems is not a logical argument.
What do the authors mean by “lower sarcopenia”? If someone has sarcopenia, it can be further
classified as severe if low muscle mass is combined with both low muscle strength and low
physical performance.
ADDITIONAL REQUESTS/SUGGESTIONS:
The written expression needs improvement throughout the manuscript. It would also be useful
to add page numbers as a minimum to make it easier for reviewers to identify specific parts of
the manuscript to improve."