1. Department of General Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
2. National Drug Clinical Trial Institution, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
3. Institute of Cancer, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
4. Department of Mathematics, Shanghai Normal University, Shanghai 200234, China