Abstract: OBJECTIVE To study pathogen distribution and its effect on serum COX2 and Ecadherin in esophageal carcinoma patients who received radiotherapy so as to provide references for clinical diagnosis, treatment and prognosis. METHODS Totally 200 cases of esophageal carcinoma patients who received radiotherapy in our hospital form Feb. 2012 to Aug. 2015 were enrolled in this study. The genotypes and distribution of pathogens were identified by VITEK-2 Compact equipment. The serum COX2 and Ecadherin as well as MMP2, C-myc and Bax/Bcl2 were detected by ELISA. A total of 200 cases of healthy subjects and 200 cases of uninfected patients at the same period in our hospital were taken as control. RESULTS The pathogens isolated from the patients included 102 (51.0%) gram positive bacteria and 98 (49.0%) gram negative bacteria. The serum Bcl2, MMP2, Ecadherin and XBIP increased greatly in infected patients while the Bax and C-myc proteins decreased significantly when compared with control. The differences were significant (P<0.05). CONCLUSION Esophageal carcinoma patients received radiotherapy suffer from pathogen infection and the abnormal expression of COX2 and Ecadherin are involved in this pathological process.