Effects of pelvic 3D-CRT versus IMRT radiation therapy on circulating pro-inflammatory cytokines in high risk Prostate Cancer patients
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This study examined the effects of pelvic radiation therapy on the levels of circulating pro-inflammatory cytokines (cPIC) in high-risk prostate cancer patients, who received pelvic radiation therapy delivered either by 3-dimensional radiation therapy pelvic (3D CRT) or intensity-modulated radiation therapy (IMRT). Subjects included 90 patients who had not previously received treatment for their prostate cancer, and who were planned to receive androgen deprivation therapy for three years, plus concurrent pelvic and prostate boost radiation therapy. Blood samples were drawn at least 3 months into androgen deprivation therapy, before initiation of pelvic 3D-CRT or IMRT (baseline), and on days 5 and 25 of radiation treatment. Samples were analyzed for TNF-α, INF-γ, IL-4, IL-6, IL-8 and IL-10. There were no significant differences between treatment groups for any of the cytokines at any time point. When the two treatment groups were combined into a single group, a significant time/dose effect was observed for IL-4 and INF-γ, which both significantly decreased from baseline to day 25, but the effect size of this change was small (0.30 and 0.24, respectively). There was no significant time effect for the other cytokines. These results suggest that in patients with high risk prostate cancer, receiving treatment with androgen deprivation therapy and pelvic radiation therapy, cPIC are not significantly altered in response to radiation therapy compared to baseline. The small but significant changes in IL-4 and INF-γ over time suggest a potential immunomodulating effect of radiation therapy. Further studies are needed to determine the potential of cPIC as biomarkers of radiation therapy toxicity.