Review for 10.1186/s12876-020-01583-7 (2021)

Reviewer’s report
Title: 
Effectiveness of introducing a 20-gauge core biopsy needle with a core
trap in EUS-FNA/B for diagnosing pancreatic cancer
Version: 
0 
Date: 
29 Sep 2020
Reviewer: 
John Leeds
Reviewer's report:
The authors describe the use of several needle types used for the acquisition of
tissue in patients undergoing EUS for pancreatic masses and compare the
characteristics of the samples and diagnostic accuracy. This is an interesting
study but has some issues which need to be addressed:
1. The main issue with this study is its retrospective design. Patients were not
randomised to a needle selection and there was no strict protocol for number of
passes into the lesion. This needs to be adequately addressed in the discussion.
2. There was no blinding of the pathologists or endoscopists as to which needle
was selected.
3. The numbers in each group are variable with the total number in the acquire
group being very low at 12 making comparison with this needle type
problematic.
4. The needles were available at different time periods. This is very important as
there may be a significant time factor where the endoscopists need to become
comfortable with a new needle as well as they had more experience as time went
on. It would be interesting to know whether there were any differences in
accuracy if the first 50 uses of each needle were compared.
5. No data is given about whether the sampling was transduodenal or
transgastric. A presentation of the comparisons of each locations would be
helpful.
6. The authors used "suspected" cancer as a positive outcome. This is no longer
acceptable as this is insufficient to be accepted for chemotherapy or entry into
clinical trials. The authors should reanalyse the results looking at "definite"
cancers also.
7. No information is given about final diagnoses in the whole cohort e.g.
percentage with pancreatic cancer, chronic pancreatitis, neuroendocrine tumours
etc.
8. There were some significant differences between the groups at the outset
which requires some commentary. The tumour size and stroke length were
significantly bigger for the PC groups as was the number of passes. Number of
passes has been shown to improve diagnostic yield alone. Once could argue
therefore that the AC group obtained just as good results but in more difficult
circumstances and in less time so perhaps this is a better needle?
9. More information is needed about the pathologists experience as they are the
ones that really matter. Were they cytopathologists or histopathologists or both.
Was there double reporting of specimens as is now common?
10. Very little comment is made about the data concerning other FNB needles for
which there are now several RCT's showing improvement over FNA needles.
Similarly, the Procore needles have been shown to be no better than an FNA
needle.
11 .The introduction feels very long and could be shortened - similarly with the
discussion.
12. The statistical reporting in the tables does not make it clear where the
differences lie e.g. the p value is <0.01 but is this for all 3 groups or just between
two of the three.
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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?
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