Title: Dietary Quality Index and the Risk of Breast Cancer: A Case-Control Study
Version: 1 Date: 25 Jun 2023
Reviewer's report:
Reviewer's report
Title: Dietary Quality Index and the Risk of Breast Cancer: A Case-Control Study
Version: 1
Date: 25 June 2023
Dear Editor
This paper investigated the association between diet quality and breast cancer in the Iranian
population. Despite the valuable topic that has been investigated, based on the items mentioned,
the method and results sections seem to have a lot of fundamental problems and ambiguities.
Introduction:
1. Line 62-63. Please provide the time interval/point for data from IARC.
2. Line 63. The word “estimate” is often used to provide a rough approximation in the future,
while the sentence referred to 2020. Please correct it.
3. Line 65. The sentence needs to be grammatically corrected.
4. Line 74-75. Please provide the reliability and validity of the questionnaire.
5. Line 78. What do you mean by “risk variables”?
6. Line 85. The sentence is redundant in the “introduction” section, and is more related to the
“method”.
Methods:
7. Line 90. While smoking could be a crucial variable related to lifestyle and diet, please
provide your rationale and justification for excluding smokers. How would you guarantee that
the observed association between diet and Breast cancer is not partly due to restricting only the
control group to non-smokers? What is the distribution of smoking in the case group?
8. How did you consider the differentiation between the effect of never-smokers and ex-
smokers?
9. Line 92. Please describe any efforts to prevent selection bias. Which hospitals have been
selected for selecting the groups? How did you ensure that the source population was the same
for the case and control groups?
10. Line 110. Please introduce the general questionnaires used to gather participants’
clinical information, lifestyle, and socio-demographic-economic, and clarify their validity and
reliability.
11. Line 111. Please clearly define all variables (including confounders) used in the analysis, in
the method section, i.e. age, family history of cancer, family history of breast cancer, and energy.
12. Line 144. As you know, a cancer diagnosis could affect the lifestyle, especially patients'
diet, and physical activity, and create a noticeable difference between the case and control
groups. Therefore, how did you modify the effect of the duration of cancer? Also, please provide
information about the duration (the time from diagnosis) of cancer in patients (min, median,
and max).
# Please consider that subgroup analyses (or adjustments) based on the time from diagnosis
might present different results.
13. The results of the ANOVA test have not been presented anywhere in the “results” section.
Results:
14. Line 151. Regarding Table 1, Please define in detail all variables mentioned in the table, in
the method section including marriage age, age at first pregnancy, breastfeeding time, variety
score, abortion history, wearing a bra during the day/night, and herbal drug.
15. Regarding the results of the chi-square test, please report the numbers besides percent.
16. Line 153. Regarding Figures 1 and 2, please provide a comparison by case and control groups
instead of the total study population.
17. Regarding Tables 2 and 3, you presented two models for the association. Which is the best
model? Which method (LR test, AIC, BIC, etc.) have you used to determine the most optimal
model?
18. Table 1 reported that 3.4 % of controls are in the “yes” category for smoking, while in line
90, it is mentioned that smoking was an exclusion criterion for the control group. What is the
justification for the disagreement?
19. Regarding Tables 2 and 3, based on which rationale, the variables have been chosen to be
adjusted in model 2? Why you did not adjust the model for smoking, age at marriage/ pregnancy
or abortion history, etc.?