Effect of irradiation on cytokine production in cancer patients.

Background: Irradiation, which affects cytokine secretion, is used to treat cancer patients. Cytokine levels have correlations to disease parameters, serving as biomarkers for patients. We aim to explore the effect of irradiation on cytokine production both in vitro (using lymphocytes from healthy donors) and in vivo (using serum levels of head and neck cancer patients following irradiation) and correlating them to mucositis severity/need for percutaneous endoscopic gastroscopy (PEG) tube installation.

Methods: Cytokine production by cultured lymphocytes from healthy donors, in vitro, following irradiation of 5 or 10 Gy. In addition, blood from 23 patients with head and neck cancers, irradiated by 60-72G in vivo, were assessed for inflammatory cytokines (tumor necrosis factor (TNF)α, interleukin (IL)-6, IL-8, IL-18), the anti-inflammatory cytokine IL-10, and the general marker sIL-2R. Following radiation, selected patients who were developing mucositis were treated by PEG tube installation. Changes in cytokine levels were studied as predictive biomarkers of response to therapy/PEG tube installation. Cytokine production levels were measured using ELISAs kits.

Results: Irradiation decreased the levels of all tested cytokines, most notably IL-6 and IL-8, proportional to irradiation dose. In patients, increases in cytokine levels, correlated with mucositis severity and potentially the need for PEG tube installation.

Conclusions: Irradiation decreased the levels of all cytokines of healthy lymphocytes in a dose-dependent manner, especially those of IL-6 and IL-8. This study shows a correlation between high and increasing levels of inflammatory cytokines, sIL-2R, plus radiation toxicity and the need for PEG. The reduction of cytokine levels after radiotherapy predicts that PEG will not be required. Thus, our study shows that cytokine changes are predictive biomarkers in head and neck cancer patients.