Background/Aim: Adjuvant radiotherapy (RT) damages multiple layers of skin, muscle, blood vessels and blood cells that are included within the RT area. Indirect, bystander systemic effects could also develop in cells not directly hit by radiation. Materials and Methods: Ninety-three female patients recovering from breast cancer surgery and 82 female healthy blood donors were analyzed. For identification of systemic adaptive and innate immune response, rapid and low-cost blood-based biomarkers were assayed. Results: Post-operated breast cancer patients had a decreased number of circulating adaptive immune response cells but increased number of circulating immunosuppressive myeloid subpopulations. RT decreased the number of T-cells and platelets without influencing the number of immunosuppressive myeloid subpopulations. Alterations in the number and phenotypes of T-cell subpopulations were associated with SNPs. Conclusion: The combination of RT and immunotherapy might provide optimal treatment for cancer patients.