Funding for this research was provided by:
Funding of Sun Yat-sen University Grant for Medical Humanities Practice and Teaching (No. 23000-18008023)
Received: 8 January 2019
Accepted: 23 May 2019
First Online: 29 May 2019
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of Sun Yat-sen University Cancer Center. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Written informed consent was obtained from individual participants included in the study. All authors signed authorization forms and received permission from SEER to access and use the dataset.
: Not applicable.
: The authors declare that they have no competing interests.