1. Department of Medicine, Division of Epidemiology; Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine; Nashville TN
2. Department of General Surgery; Tangdu Hospital, Fourth Military Medical University; Xi'an China
3. Department of Epidemiology; Shanghai Cancer Institute, Renji Hospital, Shanghai Jiaotong University School of Medicine; Shanghai China