1. Department of Gastroenterological, Breast and Endocrine Surgery, Yamaguchi University Graduate School of Medicine, Ube 755-8505, Yamaguchi, Japan
2. Department of Oncology Center, Yamaguchi University Hospital, Ube 755-8505, Yamaguchi, Japan
3. Department of Data Science, Shimonoseki City University, Shimonoseki 751-8510, Yamaguchi, Japan