Funding for this research was provided by:
Zhejiang Provincial Natural Science Foundation of China (LY15H150004)
General Research Program of Zhejiang Provincial Department of Health (201345919)
Text and Data Mining valid from 2019-07-15
Received: 16 August 2018
Accepted: 25 June 2019
First Online: 15 July 2019
Ethics approval and consent to participate
: Because patient data in the SEER database were de-identified, signed informed consent was waived for the present study.
: Not applicable.
: The authors declare that they have no competing interests.