Evaluation of psychological changes using facial emotion analysis in postoperative rehabilitation treatment for patients with upper gastrointestinal cancer: A prospective study - Naoto Seriu; Shogo Sasaki; Yukako Ishida; Yasuyo Kobayashi; Tetsuro Kitamura; Yuya Mawarikado; Yosuke Uchihashi; Yusuke Inagaki; Masayuki Sho; Akira Kido (PLoS ONE, 2026)