Review for 10.1186/s12876-021-01671-2 (2021)

Reviewer’s report
Title: 
V-Raf murine sarcoma viral oncogene homolog B1 (BRAF) as a
prognostic biomarker of poor outcomes in esophageal cancer patients
Version: 
0 
Date: 
23 Nov 2020
Reviewer's report:
This study used immunohistochemistry to detect the expression of BRAF via
tissue microarrays in esophageal cancer samples, and determine its effect on
patient outcomes. They found BRAF overexpression was significantly correlated
with low Ki67 (P < 0.05) and shorter survival (P = 0.014). Cell culture study
showed BRAF knockdown reduce colony formation, cell migration and invasion.
Xenograft animal model showed BRAF inhibition suppressed tumor growth.
Major comments:
1. What is the histological type of esophageal cancer? For example, squamous
cell carcinoma or adenocarcinoma? The data should be presented in Table 1. 
2. Did the enrolled patients receive pre-operative chemotherapy or radiotherapy?
Or did they receive post-operative chemotherapy or radiotherapy? The data
should be presented in Table 1. In addition, the treatment modality should be
included in the survival analysis (both univariate and multivariate Cox
regression), because treatment modality is an important determinant of
prognosis. 
3. In Table 1 and Table 2, it is important to clarify the definition of AJCC
staging. Are they pathological staging (determined by surgical specimen) or
clinical staging (determined by imaging studies)?
4. The expression of Ki67 is strongly associated with tumor cell proliferation and
growth. However, this study showed a negative correlation between Ki67
expression and BRAF (Table 2). Note that weak BRAF expression correlated
with high Ki67. In other words, tumor with weak BRAF expression correlated
with increased tumor proliferation. This clinical data showed a conflict result
with that of the survival data (weak BRAF correlated with better survival) and
basic studies, including cell & animal studies (BRAF knock down correlated
with reduced tumor cell proliferation). The author should explain why there is
such a conflict. 
5. In the Cox regression analysis (Table 3), it is important to show whether the
variable is treated as continuous or categorical variable. In the categorical
variable, which group is treated as referent to calculate HR? 
6. In Fig. 2, please do subgroup Kaplan Meir survival analyses in AJCC stage II
and stage III patients, respectively, to show the association between BRAF
expression and survival of patients with each stage. 
Minor comments:
1. Esophageal cancer is not the most common malignant tumor. Please correct
the mistake in the "Abstract".
2. In result, "According to the seventh edition of the AJCC staging system, 5
cases were classified as phase I, 47 were phase II, 53 were phase III." The word
"phase" should be "stage".
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Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
Yes
Are the methods sufficiently described to allow the study to be repeated?
Yes
Is the use of statistics and treatment of uncertainties appropriate?
No
Is the presentation of the work clear?
No
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes