Text and Data Mining valid from 2020-01-06
Accepted: 11 December 2019
First Online: 6 January 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 (National Cancer Center Institutional Review Board; reference no. 2017-410) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: The requirement for acquisition of informed consent from patients was waived owing to the retrospective nature of this study.