Article History
Received: 24 July 2019
Accepted: 27 July 2019
First Online: 1 August 2019
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.
: This study was approved by the Institutional Review Board of National Cancer Center, Korea (IRB number: NCC 2019-0091), and the requirement for obtaining informed consent was waived due to the retrospective nature of this study.