Received: 29 August 2020
Accepted: 18 December 2020
First Online: 6 January 2021
Ethics approval and consent to participate
: The Ethics Committee of Tokyo Medical and Dental University approved this study (#2192). The requirement for informed consent from each patient was waived because of the study’s retrospective design and the use of anonymized patient data.
: The manuscript does not include individual patient’s data. Therefore, consent is not applicable for this study.
: The authors declare that they have no competing interests.