Received: 13 June 2020
Accepted: 27 October 2020
First Online: 3 November 2020
Ethics approval and consent to participate
: This study was conducted after obtaining approval from the human research ethics committee of the Saitama Medical Center, Saitama Medical University. This study is a retrospective study using existing samples and does not require informed consent. The opt-out was posted on the homepage and the inquiries from patients were responded appropriately.
: Not applicable.
: The authors declare that they have no competing interests.