Received: 22 May 2019
Accepted: 15 July 2019
First Online: 24 July 2019
Ethics approval and consent to participate
: This study was approved by The Ethics Committee of National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences (No: NCC2018AA-015). All patients agreed that their stored material was enclosed and that their clinical data were anonymously used for statistical analysis.
: Written informed consent was obtained from the patient before publication.
: The authors declare that they have no competing interests.