Radiotherapy Effects on Immune System of Patients with Solid and Hematopoietic Tumors

Background: Radiotherapy (RT) recruits biological effectors outside the treatment field with systemic effects. Non-cancerous cells surrounding the tumor may play a pivotal role in cancer progression, as well as in metastasis. Local radiation triggers systemic effects, which in combination with immunotherapy may contribute to better treatment outcomes.
Objective: The aim of this study was to evaluate RT effects on peripheral immune system (IS) in patients with lung cancer (LC) or diffuse large B cell lymphoma (DLBCL) after external beam radiotherapy.
Methods: We studied a group of LC and DLBCL patients immediately before RT (T0), half-treatment (T1) and 30 days after the end of treatment (T2). Blood samples were analyzed by flow cytometry for CD3, CD4, CD8, CD19, CD56, CD25, CD127 FoxP3 expression. Procarta Cytokine Profiling kit was used to quantify cytokines and chemokines concentrations.
Results: In LC patients, a decrease in B, Natural Killer (NK) and cytotoxic NK cells were observed during treatment, associated with an increase of interleukin (IL)-27 and IL-7 from T0 to T1 and followed by a decrease at T2. DLBCL patients showed increased levels of induced regulatory T cells from T1 to T2 and interferon gamma (INF-γ) over time. Comparing the two pathologies, we perceived that LC patients had increased cell subpopulation levels of IL-1β, IL-2, INF-γ, IL-5 and chemokine (C-C motif) ligand 5 compared to DLBCL patients.
Conclusions: RT induces different IS responses between LC and DLBCL patients. Generally, the IS status of the patients at the beginning of the treatment can contribute to different RT treatment responses.