[1] Int Univ Hlth & Welf, Sch Med, Dept Hepatobiliary Pancreat & Gastrointestinal Sur, 852 Hatakeda, Narita, Chiba 2568520, Japan
[2] Univ Tokyo, Sch Publ Hlth, Dept Clin Epidemiol & Hlth Econ, Tokyo, Japan
[3] Univ Tokyo, Dept Cardiovasc Med, Tokyo, Japan
[4] Keio Univ, Dept Surg, Sch Med, Tokyo, Japan
[5] Tokyo Med & Dent Univ, Dept Hlth Policy & Informat, Grad Sch, Tokyo, Japan
[6] Natl Canc Ctr, Div Esophageal Surg, Tokyo, Japan