Received: 16 April 2018
Accepted: 8 May 2018
First Online: 18 May 2018
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board (IRB) of Shizuoka Cancer Center (SCC) (IRB code: 27-J104–27-1). Approval for the review of hospital records was obtained from the SCC IRB and the patients’ informed consent was obtained through opt-out methodology given the retrospective nature of the study.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.