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Article History

Received: 23 September 2020

Accepted: 5 May 2021

First Online: 18 May 2021

Declarations

:

: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee (Peking Union Medical College Hospital, S-K1055) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study. The content was verbal. Many patients lived outside Beijing, some even lived overseas, and could only offer verbal consent. The ethics committee approved this procedure as the study only involves the collection or study of existing data, documents, records, pathological specimens, or diagnostic speciments, and these sources are publicly available, or the information is recorded by the investigator in such a manner that the subjects cannot be identified, directly or through identifiers linked to the subjects.

: Not applicable.

: All authors declare that they have no conflicts of interest related to the topic.