Abstract: ObiectiveTo evaluate the application of systemic immune-inflammation indexes (SII) in assessing the prognosis of elderly patients with esophageal cancer after radiotherapy. MethodsClinical data were collected from 84 patients who received radiotherapy before retrospective analysis. The cutoff values of SII, platelet-lymphocyle ratio (PLR) and monocyte-lymphocyte ratio (MLR) were determined by ROC curve, and the relationship between SII, PLR and MLR was analyzed. ResultsThe median overall survival (OS) time was 19 months for all patients. SII and PLR in elderly patients with esophageal cancer were associated with OS (P＜0.05), rather than MLR (P=0.22). According to the area under the ROC curve, the predictive value of SII was superior to that of PLR (P＜0.05). ConclusionsSII is a strong predictive index for elderly patients with esophageal cancer after radiotherapy. The higher SII is, the worse the prognosis will become.