Clinical Research Directory

Inclusion Criteria: 1. Age 18 and older. 2. Confirmation of esophageal cancer through histopathology or cytology. 3. Primary tumor location within the cervical or upper thoracic segment, extending from the upper esophageal sphincter to the azygos vein. 4. Absence of distant metastasis. 5. Patients unable or unwilling to undergo surgical treatment for various reasons. 6. Receipt of radical radiotherapy as the first-line treatment, with or without chemotherapy, immunotherapy, or targeted therapy. 7. Undergoing conventional radiation therapy (1.8-2.0Gy per session, once per day). 8. Receiving 3DCRT or IMRT radiotherapy. 9. Availability of complete radiotherapy prescription dose information and follow-up records. Exclusion Criteria: 1. Receipt of radiation dose below 50Gy. 2. History of other malignancies (except for cured cancer in situ and malignancies cured for over 5 years) or laryngeal invasion. 3. Diagnosis of double primary esophageal cancer. 4. Prior chest radiation therapy within the past 5 years. 5. Recurrent or metastatic esophageal cancer. 6. Receipt of 2D radiotherapy, large fractionation, or hyper-fractionation radiotherapy. 7. Patients with incomplete radiotherapy dose and follow-up data.