Circulating levels of IL-6 and TGF-β1 in patients with prostate cancer undergoing radiotherapy: associations with acute radiotoxicity and fatigue symptoms.

Background: The goal of research was to investigate the possible relations between serum concentrations of IL-6 and TGF-β1, individual and clinical characteristics, and adverse effects of radiotherapy in patients with prostate cancer: acute and late genitourinary and gastrointestinal toxicity, and fatigue.

Methods: Thirty-nine patients with localized or locally advanced prostate cancer who were treated with radiotherapy were enrolled in this study. The acute radiotoxicity grades and fatigue levels were assessed during the radiotherapy and 1 month after the radiotherapy. Estimation of the late radiotoxicity was performed every three months in the first year, every four months in the second year, and then every six months. Serum levels of IL-6 and TGF-β1 were determined before radiotherapy and after the 25 radiotherapy fraction by ELISA.

Results: The significant positive association between diabetes mellitus and changes in acute genitourinary toxicity grades during the radiotherapy was observed in prostate cancer patients. In addition, patients who were smokers had significantly higher maximum fatigue levels in comparison with patients who were non-smokers. The circulating IL-6 levels were significantly higher after the 25 radiotherapy fraction in comparison with levels determined before radiotherapy. The significant positive correlations between pretreatment TGF-β1 levels and maximum genitourinary toxicity grades and between TGF-β1 levels after the 25 fraction and genitourinary toxicity grades after the 25 fraction, were found. The pretreatment IL-6 concentrations and TGF-β1 concentrations after the 25 fraction were positively correlated with maximum genitourinary toxicity grades. The IL-6 levels after the 25 fraction were positively associated with genitourinary toxicity grades after this fraction. The pretreatment IL-6 concentrations were significantly positively correlated with maximum fatigue scores. The significant positive correlation between IL-6 concentrations and fatigue scores after the 25 fraction was determined. The positive correlations between IL-6 and TGF-β1 concentrations measured after the 25 fraction and maximum fatigue scores were observed.

Conclusions: Our results suggest that serum levels of IL-6 and TGF-β1 might influence the severity of acute genitourinary radiotoxicity and fatigue in patients with prostate cancer. Combining clinical parameters and circulating cytokine levels might be useful for the prediction of adverse reactions to radiotherapy.