1. Department of Health Sciences , Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
2. Division of Cancer Epidemiology and Prevention , Miyagi Cancer Center Research Institute, Natori, Miyagi, Japan
3. Center for Preventive Medicine , Osaki Citizen Hospital, Osaki, Miyagi, Japan
4. Department of Gastroenterology , Miyagi Cancer Center Hospital, Natori, Miyagi, Japan
5. Department of Surgery , Miyagi Cancer Center Hospital, Natori, Miyagi, Japan
6. Deapartment of Epidemiology and Public Health , Kanazawa Medical University, Kahoku, Ishikawa, Japan