Funding for this research was provided by:
Shanghai Shenkang hospital development center (SHDC12018629)
Text and Data Mining valid from 2019-07-23
Received: 10 May 2019
Accepted: 18 July 2019
First Online: 23 July 2019
Ethics approval and consent to participate
: Approval for institutional review board together with written informed consent were waived for this study as SEER database is open accessible and all identity data of subjects are undistinguishable.
: Not applicable.
: The authors declared that they have no competing interests.