Review for 10.1186/s12876-020-01586-4 (2021)

Reviewer’s report
Title: 
Clinical features and outcomes of combined hepatocellular carcinoma and
cholangiocarcinoma versus hepatocellular carcinoma versus cholangiocarcinoma
after surgical resection: A propensity score matching analysis
Version: 
1 
Date: 
18 Sep 2020
Reviewer's report:
Lin et al retrospectively analyze the clinical features and outcomes of combined
HCC-CCA vs HCC vs CCA after surgical resection. After PSM, the OS and
disease free survival in the mixed HCC-CCA group were not significantly
different from those in the HCC or CCA group.
These results have been published in numerous studies, however the topic
remains important.
The cohort of HCC patients is large, but CC and mixed small contributing to the
limitations of this study
1- can the authors explain in more detail how they performed the PSM. 
2- Were the mixed or CCa cases known preoperatively based on radiology
imaging or biopsy?
3- can the authors comment on the high rate of macrovascular invasion?
4- were recurrences of mixed tumors likely to be HCC or CCa?
5- Based on these findings, do the authors suggest we should manage these
patients similarly? can the authors comment
Thank you
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