1. Multicenter Clinical Study Group of Osaka, Risk Management Group; Osaka Japan
2. Department of Surgery; Kansai Rosai Hospital; 3-1-69 Inabaso Amagasaki Hyogo 660-8511 Japan
3. Department of Surgery; Osaka Rosai Hospital; 1179-3 Nagasone-cho, Kita-ku Sakai Osaka 591-8025 Japan
4. Department of Surgery; Osaka National Hospital, National Hospital Organization; 2-1-14 Hoenzaka, Chuo-ku Osaka 540-0006 Japan
5. Department of Gastroenterological Surgery, Graduate School of Medicine; Osaka University; E2, 2-2 Yamadaoka Suita Osaka 565-0871 Japan