Text and Data Mining valid from 2020-01-06
Received: 11 June 2019
Accepted: 23 December 2019
First Online: 6 January 2020
Ethics approval and consent to participate
: All of the authors signed the “SEER Research Data Agreement” in order to protect the patients’ privacy, which is consistent with ethical principles.
: All authors listed approved the publication of the manuscript.
: The authors declare that they have no competing interests.