1. Department of Surgery, Oda Municipal Hospital , 1428-3 Oda-cho Yoshinaga, Oda 694-0063, Shimane , Japan
2. Department of General Medicine, Shimane University Faculty of Medicine , 89-1 Enya-cho, Izumo 693-8501, Shimane , Japan
3. Department of Digestive and General Surgery, Shimane University Faculty of Medicine , 89-1, Enya-cho, Izumo City 693-8501, Shimane , Japan