Funding for this research was provided by:
National Cancer Institute (P30 CA008748)
Received: 5 February 2018
Accepted: 6 May 2019
First Online: 18 June 2019
Ethics approval and consent to participate
: The study was approved by the Ethics Committee of the Pusan National University Hospital (H-1707-009-057). For this type of investigation, formal patient consent was not required. This investigation was retrospective and there were no human subjects were prospectively recruited.
: Not applicable
: The authors declare they have no competing interests.
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