PILOT-STUDY OF CYTOKINE PROFILES IN PROSTATE-CANCER PATIENTS UNDERGOING PROTON OR CONVENTIONAL RADIOTHERAPY

The mechanisms responsible for normal tissue late effects following ra diotherapy are largely unknown and currently no method for predicting such risks is available. Abnormal levels of cytokine production induce d by radiation has been suggested as a contributing factor by multiple investigators. The purpose of the present study was to evaluate plasm a levels of transforming growth factor-beta 1 (TGF-beta 1), basic fibr oblast growth factor (bFGF), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1 beta (IL-1 beta) in patients with prostate cancer sc heduled for radiotherapy (protons, photons, or combination of both). I t has been recently shown that ionizing radiation can increase express ion of these cytokines and there are indications that they may be asso ciated with morbidity. Blood samples were obtained from 20 subjects (a ge 51-80) before, during the first week, and immediately after the end of therapy; 3 healthy volunteers served as controls. Significant posi tive correlations (p<0.05) were obtained between bFGF, IL-1 beta, and TNF-alpha and the integral dose of radiation during the first week of treatment. Correlations approaching significance (p<0.1) were obtained with bFGF and acute treatment-related morbidity. A higher integral do se (due to larger irradiated volumes) was delivered with conventional photon compared to proton irradiation. No significance was obtained wi th any of the cytokines and pretreatment prostate specific antigen (PS A) levels, patient age, grade or stage of disease, or the integral dos e by the end of radiation treatment. These results show that large cha nges occur in the plasma levels of certain cytokines early after initi ation of radiotherapy and that treatment of larger volumes is more lik ely to induce these changes. Our data support further investigation of the role of cytokines during radiotherapy.