1. Department of Surgery and Science, Faculty of Medicine, Academic Assembly, University of Toyama, Toyama 930‑0194, Japan
2. Department of Surgery, Toyama Nishi General Hospital, Toyama 939‑2716, Japan
3. Department of Surgery, Toyama Prefectural Central Hospital, Toyama 930‑8550, Japan
4. Department of Surgery, Takaoka City Hospital, Takaoka, Toyama 933‑8550, Japan
5. Department of Surgery, Tonami General Hospital, Tonami, Toyama 939‑1395, Japan
6. Department of Surgery, Kouseiren Takaoka Hospital, Takaoka, Toyama 933‑8555, Japan
7. Department of Biomedical Statistics and Bioinformatics, Kyoto University, Kyoto 606‑8501, Japan