1. From the Colorectal Cancer Center, Department of General Surgery (Y.S., W.M., M.W., M.Q., Z.W.), and Department of Radiology (X.G., H.Z.), West China Hospital, Sichuan University, No. 37 Guo Xue Xiang St, Chengdu 86610000, China; and Department of Epidemiology and Medical Statistics, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China (Y.H.).