Baolei Zhang1, Tangshuai Liang1, Guodong Ru2. 1. Department of Gastrointestinal Surgery, Liaocheng People's Hospital, Liaocheng, 252000, People's Republic of China. 2. Department of General Surgery, Liaocheng Tumor Hospital, Liaocheng, 252000, People's Republic of China. lcruguodong@126.com.