Received: 21 July 2020
Accepted: 18 September 2020
First Online: 24 September 2020
Ethics approval and consent to participate
: This study was approved by the institutional review board (IRB) of the Medical Ethical Committee of Chiba University Graduate School of Medicine (Chiba, Japan), and written informed consent was waived due to the retrospective nature of this study (IRB Number 3594).
: Not applicable.
: The authors declare that they have no competing interests.