Department of Oncology;
Xijing Hospital;
The Fourth Military Medical University;
Xi'an 710032;
Shaanxi;
China;
Department of Oncology;
Affiliated Hospital of the Academy of Military Medical Sciences;
Beijing 100039;
China;
Department of Gastroenterology;
Nanfang Hospital Guangzhou 510515;
Guangdong;
China;
Department of Pathology;
University of Vermont;
208 South Park;
Dr. Suite 2;
Colchester;
VT05446;
U.S.A.;
Department of Epidemiology;
the Fourth Military Medical University;
Xi'an 710032;
Shaanxi;
China;