1 Department of Digestive Surgery, Niigata Cancer Center Hospital, Niigata, Japan. y-hirose@med.niigata-u.ac.jp.
2 Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata City, Niigata, Japan. y-hirose@med.niigata-u.ac.jp.
3 Department of Digestive Surgery, Niigata Cancer Center Hospital, Niigata, Japan.
4 Department of Pathology, Niigata Cancer Center Hospital, Niigata, Japan.