Objective To investigate the change of gastroesophageal reflux including acid reflux,duodenogastroesophageal reflux (DGER) and its effect on expression of COX-2 and TNF-α in the remnant esophagus in different period after esophagectomy for cancer.Methods Thirty-two patients who underwent esophagectomy for cancer were selected randomly.Twentyfour-hour pH and spectrometric bilirubin monitoring,endoscopy were periodically performed.Esophageal mucosa samples were obtained by endoscopic biopsy.Expression of COX-2 and TNF-α within remnant esophageal mucosa was detected using immunohistochemical assay.Results ( 1 ) The incidence of reflux esophagitis and extent of acid reflux gradually increased over time after surgery for cancer ( P ＜ 0.05 ).(2) Very low level of COX-2 and TNF-α expression was detected in normal esophageal squamous mucosa.The expression of COX-2 and TNF-α was observed in cytoplasm of basal cell of esophageal epithelium after esophagectomy for cancer.High intensity of COX-2 and TNF-α expression was detected in the metaplastic columnar mucosa.The level of TNF-α expression in the remnant esophagus where reflux esophagitis occurred was higher than that in the normal remnant esophagus ( P =0.0274 ).There was no significant difference in level of COX-2 expression in the remnant esophagus between reflux esophagitis occurred and not ( P =0.7403 ).Conclusion ( 1 ) The extent of acid reflux and incidence of esophagitis gradually increases over time.(2) The expression of COX-2 and TNF-α may represent an early change associated with gastroesophageal reflux.The expression of COX-2 may serve as a molecular marker of gastroesophageal reflux occurred.( 3 ) The durative expression TNF-α is likely involved with the pathogenesis of chronic reflux esophagitis.