Review for 10.1186/s12876-020-1171-1 (2020)

Reviewer’s report
Title: Comparison of the effects of adjuvant concurrent chemoradiotherapy and chemotherapy for
resected biliary tract cancer
Version: 0 Date: 11 May 2019
Reviewer: Masashi Kanai
Reviewer's report:
Authors retrospectively compared the effects of adjuvant CCRT and chemotherapy for resected BTC.
They concluded that adjuvant CCRT was significantly superior to chemotherapy in RFS and OS.
However, based on the data showen in this manuscript, this reviewer is not sure whether adjuvant
CCRT can really contribute to the significant improvement of OS for resectable BTC
Major comments
1.  Authors  concluded  that  "Our  study  demonstrated  the  superiority  of  adjuvant  CCRT  over
chemotherapy for improving RFS and OS in curatively resected BTC." However, their data did not
show significant improvement in OS (Figure 1) and this sentence should be re-considered. 
2. It is reasonable to add CCRT for patinets with positive resection margin; however, 16 patients
(34.8%) with negative resection margin also received adjuvant CCRT. Please describe possible reasons
why CCRT was selected in these patients? 
3. Locoregional recurrence free survival should be shown in Kaplan-Meier curve.
Minor comments
1. "adjuvant chemoradiotherapy (P = 0.49, OR 0.61) had significantly improved OS" (p11, line 21).
Please verify this P value is correct. 
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.
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 statistical 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:
Acceptable
Declaration of competing interests
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or has applied for patents relating to the content of the manuscript?
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