Reviewer’s report
Title: 
Night-shift work duration and breast cancer risk: an updated systematic
review and meta-analysis
Version: 
1 
Date: 
04 Dec 2020
Reviewer's report:
This systematic review and meta-analysis aimed to update the current evidence
regarding relationship between night-shift work duration and breast cancer risk. 
The object of study is interesting and is within the scope of BMC Women's
Health. However, some adjustments are necessary before its publication.
1) In methods section, the authors do not mention the use of Google Scholar for
the search of articles. However, search results in this data source have been
described in the result. It is important to properly inform the data sources used in
the research.
2) The second exclusion criterion presented by the authors is not adequate, since
the types of studies cited were not even included in the study.
3) The authors do not describe whether the systematic review was properly
protocoled or registered. According to the PRISMA guidelines it is important to
indicate if a review protocol exists, if and where it can be accessed (e.g., Web
address), and, if available, provide registration information including registration
number.
4) On lines 129-132, there is an excerpt that is part of the discussion section ("...
identified all articles included in the previous reviews (11, 18, 23). A similar
meta-analysis has been recently published investigating the effect of night-shift
work on several cancers including BC rather than considering night-shift work in
separate duration categories (27). ")
5) Table 3 was not presented in the section and Table 4 was referenced in the
text before Table 3.
6) The explanation of subgroup analysis should be part of the methods section.
7) The authors did not adequately highlight the results of the meta-analysis in the
section. These results must be given greater prominence.
8) The titles of Figures and Tables are incomplete and do not clearly show the
results.
9) Table 3 is not necessarily a result of the study. Therefore, I recommend that it
be excluded from the manuscript.
10) In the conclusion section, the use of citations is not recommended.
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Declaration of competing interests
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questions:
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paper?
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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?
Yes
Is the presentation of the work clear?
No
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes