Funding for this research was provided by:
Deutscher Akademischer Austauschdienst (57147166)
Received: 13 February 2020
Revised: 9 August 2020
Accepted: 12 August 2020
First Online: 1 September 2020
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: 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. SEER data are anonymized and considered non-human subject research. Thus, it is IRB approval and HIPAA is exempted.
: Not applicable.