Article History
Received: 22 August 2019
Accepted: 23 December 2019
First Online: 28 January 2020
Ethics approval and consent to participate
: All participants signed informed consent forms and no patients had received chemotherapy or radiotherapy before surgery. This study got approval from the ethics committee of the First Affiliated Hospital of Zhengzhou University.
: Not applicable.
: The authors declare that they have no competing interests.