Review for 10.1186/s12876-018-0886-8 (2018)

Reviewer ’s report  
 
Title: Efficacy and safety of chemotherapy after endoscopic double stenting for malignant 
duodenal and biliary obstructions in patients with advanced pancreatic cancer: a single -
institution retrospective analysis.  
 
Version: 0 Date: 08 Mar 2018  
 
Reviewer: Benjamin Tan 
 
Reviewer's report:  
 
This is a retrospective review of a single institutio n experience assessing the safety and efficacy 
of chemotherapy after a double stenting procedure for patients with advanced pancreatic cancer. 
Fifty patients were reviewed and 21 patients had various types of chemotherapy administered, 
while 29 patients di d not receive chemotherapy after double stenting. The authors concluded that 
chemotherapy after double stenting is manageable, and may potentially prolong survival in 
pancreatic cancer patients.  
1. The timing of the double stenting in relation to the line of treatment of pancreatic cancer is 
relevant and should be clarified by the authors.  Of the 50 patients, 26 had prior 
chemotherapy, but only 12 patients with prior chemotherapy received chemoth erapy 
afterwards.  Of the 14 patients who presented with simultaneous obstruction, 9 of these 
proceed with frontline chemotherapy.  Overall survival was calculated based on date of 
diagnosis regardless of the timing of stenting.  Thus, there is an inherent  and significant bias 
for patients who were able to receive chemotherapy after stenting compared to those who had 
various reasons to preclude chemotherapy; and the timing of the need for double stenting, 
whether upfront or later after initial or second che motherapy, can also impact outcomes.   
A recommendation is for the authors to determine survival times for those with upfront double 
stenting and frontline chemotherapy and compare this with those with obstruction later in the 
course of their disease? Thi s can then be compared with those who never had any chemotherapy.  
Another possibility is to compare those who had any chemotherapy, whether pre - or post stenting 
to those who never had any chemotherapy. Also,  how many of these patients have locally 
advan ced, non -metastatic disease vs those with metastatic disease as survival is much poorer for 
those with evident metastases.  What are the survival times for those in second or third line 
chemotherapy compared to frontline chemotherapy after double stenting?  
I agree with the authors that the variety of chemotherapy used and the lines of therapy is one of 
the major limitations of this study.  
 
2. A comparative analysis of a cohort of pancreatic cancer patients in the same institution who 
were treated with chemot herapy and did not undergo double stenting may be a reasonable 
control. other than survival, the differences in tolerance to post -stent chemotherapy can also 
be compared with those not requiring double stenting.  
 
3. Was there a survival difference for pa tients who had synchronbous vs metachronous double 
stenting?  
 
4. Did any of the patients have prior surgery or radiation therapy?  
 
5. Page 12, line 46 stated that "all of the procedures were successful" for those patients with 
stent dysfunction and treated  with reintervention.  However, line 52 states that 1 experienced 
clinical failure. please reconcile.  
 
6. For biliary stenting, what are the stent dysfunction rate for plastic vs metal?  
 
7. What is the median follow -up for patients assessed for stent dysf unction (both duodenal and 
biliary?  I.e how long was the follow up period when 6 developed duodenal stent dysfuction.  
if the follow -up is longer, would you have more patients developing dysfunction?  
Are the methods appropriate  and well described?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
No 
 
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 s tatistical review is recommended, please specify what aspects require further  
assessment in your comments to the editors.  
 
I recommend additional statistical review  
 
  
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Needs some language corrections before being published  
 
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 publication 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 p ublication of this manuscript, either now or in the future?  
 
3. Do you hold or are you currently 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  
 
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