Funding for this research was provided by:
National Natural Science Foundation of China (81400810)
Received: 2 January 2019
Accepted: 27 May 2019
First Online: 5 June 2019
Ethics approval and consent to participate
: This study protocol was approved by the ethical review board of Fudan University Shanghai Cancer Center. Informed consent was waived because of the retrospective nature of the study.
: Not applicable.
: The authors declare that they have no competing interests.