Changes in the immune status of patients with metastatic solid tumors during stereotactic radiation therapy: dependence on dose and amount of irradiated metastasis

Abstract

Purpose. To evaluate immunological status in patients with metastatic forms of solid tumors before and at different intervals after stereotactic body radiation therapy (SBRT) of metastatic lesions depending on the dose and the number of irradiated metastasis.

Materials and methods. A quantitative assessment and analysis of blood immunological parameters was conducted before irradiation, via 3-4 weeks and via 6-8 weeks after SBRT in patients with malignant tumors with oligometastases in the liver and lungs, in groups with a total focal dose (TFD ≤ 45 Gy ) and TFD> 45 Gy, and also in groups with irradiation of one metastases and two or more. All peripheral blood samples were analyzed by flow cytometry. Statistical analysis was performed using Friedman and Nemenyi criteria.

Results. 3-4 weeks after the end of SBRT, when using higher doses (TFD> 45 Gy), we observed statistically significant increase of T-lymphocytes (CD3⁺CD19^-); T-helpers (CD3⁺CD4⁺); activated T-helpers (CD3⁺CD4⁺HLA-DR⁺); activated cytotoxic T-lymphocytes (CD3⁺СD8⁺HLA-DR⁺). Decreasing of B-lymphocytes (CD3⁺CD19^-) was observed in both dose groups (TFD ≤ 45 Gy and TFD > 45 Gy). We also noted the activation of the T-cell link of immunity both in the group with irradiation of one metastatic lesion, and in the group where 2 or more metastases were exposed to irradiation.

Conclusion. Using of higher doses of SBRT is associated with a more activated antitumor T-cell immune response, while the analysis of groups of patients with different ammount of irradiated metastasis currently requires further research.