Behaviour of interleukin-2 serum levels in advanced non-small-cell lung cancer patients: relationship with response to therapy and survival

Interleukin(IL)-2 is a T helper (Th) 1 type cytokine that has been shown to play an important role in antitumour immune responses. In this study, the prognostic significance of serum IL-2 levels was investigated in 60 advance d non-small-cell lung cancer (NSCLC) patients. IL-2 serum levels were deter mined before chemotherapy, at the end of chemotherapy and during follow-up, using a commercially available enzyme-linked immunoadsorbent assay kit. Th e results were analysed according to the response to therapy and were used to generate a model predicting overall survival and time to treatment failu re. All 60 patients were shown to have higher IL-2 serum levels than contro ls ( P < 0.0001). Stage IV patients had significantly lower IL-2 levels tha n stage III patients (P < 0.0001), although they were still significantly h igher than controls (P < 0.0001). It is interesting that, when patients wer e divided into responders and non-responders according to the response to t herapy, the former were shown to have significantly high pre-chemotherapy l evels than the latter (P < 0.0001). Moreover, a further significant increas e in IL-2 serum levels (P = 0.004) and a significant decrease (P < 0.0001) were shown in responders and non-responders, respectively at the end of the therapy. Using univariate and multivariate analyses, both overall survival and time to treatment failure were shown to be affected by the mean pathol ogical levels of IL-2. Furthermore, the prognostic significance of the seru m level of IL-2 was confirmed by the stepwise regression analysis. In concl usion, determination of pre-treatment IL-2 serum levels was shown to be of independent prognostic utility in patients with advanced NSCLC; therefore, its possible use for prediction of outcome is proposed.