Review for 10.1186/s12876-020-01431-8 (2020)

Reviewer ’s report  
 
Title: Metastatic Pancreatic Adenocarcinomas Could be Classified into M1a and M1b Category  
by the Number of Metastatic Organs  
 
Version: 0 Date: 24 Jun 202 0 
 
Reviewer's report:  
 
In this study, Wei Cai et al. assess prognostic parameters in metastatic pancreatic cancer patients 
according to the number of metastatic organs (single vs. multip le). 
 
I think the analysis is relevant considering that prognostic differences have been observed 
between these patient groups in malignancies of other organs. However, I have several 
suggestions to improve the manuscript as follows:  
 
1. In the Abstract, t he "Background" section describes the aim of the study, but no 
background is provided.  
2. The conclusion of the abstract (and the study) ("Surgery was recommended for M1a 
patients but not for M1b patients") is too far -reaching. I would recommend stating so mething 
like "Surgery was associated with lower mortality in M1a patients but not significantly in M1b 
patients".  
3. The authors state (Background, page 5, line 17): "According to the current clinical 
guidelines for PC patients without distant metastasis, radical surgery is regarded as the primary 
treatment strategy". It might be useful to still highlight that many patients without distant 
metastasis cannot be operated radically due to the location/local extension of the tumor.  
4. The authors cite the previ ous study of Oweira et al., stating that their result "may be 
caused by their inappropriate inclusion criteria". This statement would need more clarification.  
5. I would recommend specifying the mean/median follow -up time in addition to the 
range, as well as the numbers of events in the survival analyses.  
6. Please specify how the assumptions of Cox regression were verified.  
7. In Table 1, it could be informative to list the frequencies of different metastatic sites in 
different study groups.  
8. In Tables 2  and 3, it could be helpful to report the number of patients (and the number 
of events) in each subcategory  
9. The authors have used Kaplan -Meier analysis to demonstrate that patients with single 
metastasis (M1a) had better survival outcomes than those wit h multiple metastases (M1b). I 
would recommend also analyzing if this association is significant after adjustment for potential 
confounding factors using Cox regression.  
10. The authors interpret their results (discussion, page 8, line 48): "Surgery was an 
independent prognostic factor for M1a patients rather than M1b patients." I would recommend 
further specifying that similar, but not significant survival benefit tendency wa s observed in M1b 
patients, and interpret the findings taking this into account.  
 
 
 
Publons Reviewer Recognition . Springer Nature can send verification of this review directly to  
Publons (a subsidiary of Clarivate Analytics). If you would like to take advantage of this service,  
please click on the “Yes” option below. Your name, email address, title of the reviewed  
manuscript, name of the journal, and date of your review submission (the “Review Data ”) will  
then be transmitted to Publons upon publication of the manuscript. If you have already registered  
at Publons, they will notify you of the receipt of this review and update your profile as per your  
settings and their policy. If you are not registered with Publons, you will receive an email from  
them asking you to register in order for them to be able to recognize your review on your new  
profile page. Publons may use the Review Data to generate derivative metadata for the benefit of  
Publons and you as a reviewer, carefully considering the sensitivity of such information. For  
example, Publons may verify your record as a reviewer by updating your profile published on its  
webservice if you have registered for such service or help editors to identify candidate reviewers.  
Please find the details of processing in Publons ’ privacy policy https://publons.com/about/terms  
 
Yes 
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
No 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Yes 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors . 
 
No 
 
Are you able to assess any statistics in the manuscript or would you recommend an  
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further  
assessment in your comments to the editors . 
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
 
 
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following questions:  
 
1. Have you in the past five years received reimbursements, fees, funding, or salary from an  
organisation that may in any way gain or lose financially from the publi cation of this  
manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation that may in any way gain or lose  
financially from the publication of this manuscript, either now or in the future?  
 
3. Do you hold or are you curr ently applying for any patents relating to the content of the  
manuscript?  
 
4. Have you received reimbursements, fees, funding, or salary from an organization that 
holds  or has applied for patents relating to the content of the manuscript?  
 
5. Do you have any  other financial competing interests?  
 
6. Do you have any non -financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have no competing interests' 
below.  If your reply is yes to any, please give details below.  
 
I declare that I have no competing interests  
 
Reviewer Publication Consent. I agree for my report to be made available under an Open 
Access  Creative Commons CC -BY License ( http://creativecommons.org/licenses/by/4.0 ) if this 
manuscript  is accepted for publication. Any comments that I do not wish to be included in the 
published  report have been included as confidential comments to the editor, which will not be 
published.  If you are not happy for us to publish this report, please contact the editorial office 
before completing  the review.  If you wish, you can include your name in your published report. 
Please note you must  decide whether to include your name at the start of the process and confirm 
this decision whenever  prompted. If you change y our decision later, we will not be able to 
publish your name.  
 
I agree to the terms of the CC -BY 4.0 license; please do not publish my name with my report.  
(default)