Funding for this research was provided by:
Ministry of Science and Technology of the People's Republic of China (2016YFC0105207)
Text and Data Mining valid from 2019-11-08
Received: 12 June 2019
Accepted: 16 October 2019
First Online: 8 November 2019
Ethics approval and consent to participate
: The Institutional Review Board (IRB) of Peking Union Medical College Hospital (PUMCH) reviewed the protocol. This is a retrospective study. The protocol is rational and scientific. The study accords with principle of ethics. The IRB thus approve the protocol. This is a retrospective study and written human subject consent was unnecessary.
: Not applicable.
: The authors declare that they have no competing interests.