Funding for this research was provided by:
National Natural Science Foundation of China (21375011)
Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences (No. 2017-I2M-B&R-03)
Text and Data Mining valid from 2019-08-05
Received: 16 April 2019
Revised: 3 June 2019
Accepted: 1 July 2019
First Online: 5 August 2019
Compliance with ethical standards
: The study was approved by the ethics committee of Cancer Hospital, Chinese Academy of Medical Sciences (CHCAMS) according to the Declaration of Helsinki.
: The authors declare that they have no competing interests.