1. Department of Diagnostic Pathology, Ota Memorial Hospital, SUBARU Health Insurance Society, 455-1 Oshima, Ota City 373-8585, Gunma, Japan
2. Department of Digestive Surgery, Shioya Hospital, International University of Health and Welfare, Yaita City 329-2145, Tochigi, Japan
3. Department of Frontier Surgery, Graduate School of Medicine, Chiba University, Chiba City 263-8522, Chiba, Japan