Multi-institution retrospective study of the onset frequency of postoperative pneumonia in thoracic esophageal cancer patients Yasuhiro TsubosaHiroshi SatoYuji TachimoriNobukazu HokamuraMasao Hosokawa • Yoshihiro KinoshitaHiroyuki DaikoHarushi UdagawaMasaki UenoYasuyuki SetoKeiichi Jinbo • Yuko KitagawaHiroya TakeuchiMijong ParkShiori NagasakaHiroshi YamadaYojiro Ota

Background Esophagectomy for thoracic esophageal cancer is a highly invasive procedure. Most studies analyzing the risk factors for pulmonary morbidity were conducted in the early 1990s. However, previous studies did not use fixed diagnostic criteria for postoperative pneumonia and reported widely varying onset frequencies. Purpose To define postoperative pneumonia diagnostic criteria, clarify the onset frequency of postoperative pneumonia after esophagectomy in accordance with these criteria, and investigate the risk factors of postoperative pneumonia. Methods Risk factors for postoperative pneumonia were analyzed in 615 patients who underwent esophagectomy