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: 0 Date: 11 Sep 2021
Reviewer's report:
However, there are still some points over this investigation are needed to be clarified. Each point
was classified as major or minor by its relevance to the relationship of potential confounding
(bias) or misunderstanding.
# Major
1. In the title, definitive concurrent chemoradiotherapy implied the role of treatment as curative,
however, totally more than 10 patients in both groups were reported to have distant metastasis.
No curable treatment was reported for the metastatic esophageal cancer till now.
2. The association among sarcopenia and other clinical variables was listed on the result section
of abstract, but no any analysis either design or result shown in the article.
3. In the most retrospective study, the diagram showed how to select the patients and how to
exclude patients should be provided in accordance with “STROBE” guideline.
4. How the patient chose to receive concurrent or sequential chemoradiotherapy? Are there any
criteria in the institute?
5. The R/T dose varies large among all patients, how did the radiation oncologist decide the
prescribed dose?
6. According to the reference [7], the visceral adipose tissue was calculated by different HU.
However, in this study, you just use subtraction, could you provide the reference for this
definition?
7. For building models, the importance of variable selection can’t be overemphasized. How do
you decide to use these variables?
8. In addition, some traditional important prognostic factors of esophageal cancer, like co-
morbidity or performance status was not selected, could you provide the reasons why these
factors are excluded?
9. Since the overall survival is the primary endpoint, and there were some finding on the
statistical analysis, it should be reported first.
10. The content of the table was totally not compatible with the article; for example the HR
of albumin (<40 vs >= 40) is 0687, but it was stated that patients with high albumin level had
better PFS in the article !
11. From the survival curves shown on 3B, 3D, 3E, and 3F, the curves are crossed, it seemed
proportional hazard assumption was not obeyed. Could you consider advanced survival analysis,
like time-dependent Cox model? (it is also obvious for some small plots in figure 4.)
# Minor
1. Since the serum albumin level was available, why was the nutritional risk index (NRI) not
included in the survey?
2. In the section of materials and methods, the incomplete medical record means lack what?
3. For defining the multivariate model, the way of picking up variables and exclusion.
4. The distribution of the current or sequential chemoradiotherapy between the two groups was
not available.
5. The continuous variable, like the age, BMI, the length of esophageal tumor and the level of
albumin were categorized. Could you provide the rationale of the classification rule?
6. At table one, obesity group was provided, and it was not clearly defined in the materials and
methods.
7. At table one, the criteria of SATI, VATI, and TATI were not stated.
8. English editing is necessary and it would make the article more clear.