For both cytokines a statistically significant correlation was found between the amount of pre-RT plasma levels and the staining intensity of the corresponding tumour biopsies, suggesting that -irrespective of the subsequent irradiation- the IL-6 and TGF-β1 plasma levels in NSCLC patients were influenced to a great extent by the cytokine release of their tumours (IL-6: r = 0.67, p<0.0001; TGF-β1: r = 0.83, p<0.0001). The gene discussed is TGFB1; the disease is non-small cell lung carcinoma.