摘要Objective This study aimed to investigate the effect of radiotherapy on serum immune-associated cells and tumor markers in patients with esophageal cancer. Methods A total of 87 patients with esophageal cancer admitted to our hospital between October 2016 and July 2020 were selected as the observation group, and all patients received radiotherapy. A total of 87 healthy volunteers who underwent physical examination at our hospital during the same period were selected as the control group in order to compare the changes in serum immune-associated cells and tumor markers between the two groups. Results The levels of carcinoembryonic antigen (CEA), cancer antigen (CA) 125, CA72-4, C-terminus of cytokeratin (CYFRA) 21-1, and squamous cell carcinoma (SCC) antigen in the observation group before radiotherapy were higher than those in the control group, and the differences were significant (P < 0.05). The levels of CEA, CA125, CA72-4, CYFRA21-1, and SCC antigen in the research group after radiotherapy were significantly lower than those before radiotherapy, but were still significantly higher than those in the control group (P < 0.05). The levels of CD3+, CD4+, CD4+/CD8+, and natural killer cells in the research group before and after radiotherapy were significantly lower, while the levels of Treg and CD8+ cells were significantly higher than those in the control group (P < 0.05). The levels of CD3+, CD4+, and CD4+/CD8+ cells in the observation group after radiotherapy were lower, while the levels of CD8+ cells were significantly higher than those before radiotherapy (P < 0.05). Conclusion Radiotherapy can effectively reduce the level of serum tumor markers in patients with esophageal cancer; these antigens and cells can be used as tumor markers of esophageal cancer in order to determine its prognosis. However, radiotherapy has adverse effects on the immune function of the body. The reasons behind this need to be further studied and analyzed.