Received: 11 August 2020
Accepted: 24 September 2020
First Online: 2 October 2020
Ethics approval and consent to participate
: This study was approved on March 15, 2017 (Hokkaido University Hospital Review Board 017–0296). Written informed consent was obtained from all patients before enrolment.
: Not applicable.
: The authors declare that they have no competing interests.