Interleukin-Iß plasma levels decrease following local radiation therapy for breast cancer

Exogenous interleukin-1 (IL-1) has been shown to confer radioprotection to normal tissues. However, there is little information on the effects of radiotherapy on endogenous cytokine production. The purpose of this study was to examine the influence of breast radiotherapy on plasma IL-1 levels and lymphocyte subpopulations in patients with early-stage breast cancer. IL-1 and lymphocyte subsets were determined in 13 patients before and after radiation therapy utilizing specific immunologic assays. Local radiation to the breast caused significant reduction in plasma IL-1 levels (mean 269 ± 177 vs. 3 ± 50 pg/ml, P < 0.01). This was accompanied by a marked decrease in the lymphocyte counts of all patients (1850 ± 560 vs. 1013 ± 344, P < 0.05). Local radiotherapy can have a significant effect on systemic cytokine levels that may potentially impact on the radiation response of normal tissues and tumors. To our knowledge this is the first report of the effect of local radiotherapy on plasma levels of IL-1. It is hoped that this may provide further insights into the biological responses to radiation and their impact on clinical outcome. © 1995 Wiley-Liss, Inc.