Review for 10.1186/s12876-023-02749-9 (2023)

Title: Development and validation of nomograms for predicting overall survival and cancer-
specific survival in elderly patients with locally advanced gastric cancer: a population-based
study
Version: 2 Date: 20 Feb 2023
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?
Yes - the approach is appropriate
EXECUTION - Are the experiments and analyses performed with sufficient technical rigor to
allow confidence in the results?
No - there are major 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 - 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?
Maybe - with major revisions
PEER REVIEWER COMMENTS:
GENERAL COMMENTS: In general, the authors have done a good job addressing the
comments of the three reviewers. However, there are still some remaining issues that need to
be clarified or addressed.
REQUESTED REVISIONS:
While the authors used the X-tile bio-informatics tool for their analysis, only three published
studies using the software were found on PubMed, contrary to the authors' claim that it is 'widely
used.' As a result, the reliability of the software is uncertain.
The clinical value of results of DCA were not discussed as Reviewer commented.
In the endnote of Table 1, it says “b means comparing the training cohort, internal validation
cohort with the external validation group."". Does it mean that the training and internal validation
cohorts were combined as one cohort then compared with the external validation group?
Why the C-index of training cohort is smaller than those of internal and external validation, it
should be discussed.
The x-axis of the ROC curves should be 1-specificity instead of false positive rate. The authors
should check their analysis again.
As noted by Reviewer 3, there are still significant language issues present in the revised
manuscript, including spelling errors in the rebuttal letter. To address these concerns, we
recommend having the paper proofread by an expert who is proficient in English.
I also have two issues that I would like to point out, which I believe the authors may wish to
incorporate into their discussion:
Regarding the choice to start the X axis at zero for each variable in a nomogram, it is a matter of
convention and preference. There is no strict rule for this, and it often depends on the specific
context and the purpose of the nomogram. In some cases, starting the X axis at zero can make
it easier to understand and interpret the relationship between the variables, while in other cases
it may not be necessary or appropriate. Ultimately, the choice of whether or not to start the X
axis at zero should be based on what best serves the goals of the nomogram and the needs of
the intended audience.
Whether or not to categorize continuous variables in regression analysis depends on the specific
circumstances and goals of the study, as well as the nature of the data and the relationships
between the variables. Categorizing continuous variables can be helpful in cases where there is
a nonlinear relationship between the predictor and outcome variables, and it may be difficult
to find a suitable model to fit. While splines can be used as an alternative, they can be
computationally intensive."