Radiotherapy.
D004938:Esophageal Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D006801:Humans; D009362:Neoplasm Metastasis; D011832:Radiation Injuries; D011878:Radiotherapy / Q000009:adverse effects; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy; D013997:Time Factors