Text and Data Mining valid from 2019-09-03
Received: 25 April 2019
Accepted: 21 August 2019
First Online: 3 September 2019
Ethics approval and consent to participate
: This study was approved by the medical ethics committees of Shandong Cancer Hospital Affiliated to Shandong University and informed consent was waived.
: Not applicable.
: The authors declare that they have no competing interests.