Funding for this research was provided by:
National Natural Science Foundation of China (No.16BGL183)
Research Fund of Health Bureau of Xi’an (No.QFO1330)
Received: 4 December 2018
Accepted: 30 June 2019
First Online: 5 July 2019
Ethics approval and consent to participate
: The SEER program database is publicly available and provides de-identified case data. Owing to the data of SEER program is anonymous and cancer is a reportable disease in every state, the requirement for informed consent was therefore waived by the s in the US [CitationRef removed].
: Not Applicable.
: The authors declare that they have no competing interests.