Article History
Received: 10 May 2020
Accepted: 5 August 2020
First Online: 11 August 2020
Conflict of interest
: The authors declare that they have no conflict of interest.
: This is an observational study. The Research Ethics Committee of Shengjing Hospital affiliated China Medical University has confirmed that no ethical approval is required.
: The information was accessed from the SEER database, and the requirement for informed consent was exempted by the Review Board of Shengjing Hospital affiliated China Medical University.