Funding for this research was provided by:
national cancer center, Korea (NCC-1910180)
Received: 16 December 2020
Accepted: 20 April 2021
First Online: 1 May 2021
: This study was approved by the Institutional Review Board of National cancer center, Korea (IRB No. NCC2019–0272), and the requirement for informed consent was waived because of the retrospective nature of the present study. This study was conducted in accordance with the Declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.