Abstract : Cancer refers to diseases where abnormal cells multiply uncontrollably and have the potential to spread to other tissues. Radiotherapy is one type of treatment used to treating patient with cancer, Through DNA damage, radiotherapy causes the death of malignant cells. Many of the antitumor effects of radiotherapy are caused by a direct link between it and the immune system. Radiation therapy has anticancer effects throughout the body in addition to the direct cytotoxicity it has on tumor cells. Study the impact of radiation on the levels of circulating interferon-gamma (IFN-γ), tumor necrosis factor (TNF-α) and CD8+ cytotoxic T cells. 90 women participated in this study, and they were split into three primary groups: Group I: 30 individuals with stage II-stage III invasive breast cancer; Group II: The same 30 patients After Radiotherapy, Group III: 30 healthy women as a control group. After surgery and chemotherapy, all patients in the study got adjuvant radiation. The enzyme-linked immunosorbent test was used to quantify TNF-α, INF-γ, and CD8+ cytotoxic T cells. There was a significant increase occurred in the percent of TNF-α, INF-γ, and CD8+ cytotoxic T cells between Group I patients and Group III control. A significant decrease occurred in the percent of both INF-γ, and CD8+ cytotoxic T cells between Group I patients and Group II patients After Radiotherapy, while no significant changes occurred in the percent of TNF-α between Group I and Group II. The soluble and cellular immune response mediators were altered by radiotherapy following radiation treatment; circulating cytokines in breast cancer patients were assessed. Serum level of INF-γ and CD8+ decreases after radiotherapy while no significant change in TNF- α level.