Purpose: To explore the application of interleukin (IL)-1alpha and IL-6 measurements in the predictive diagnostic testing for symptomatic radiation pneumonitis (RP).
Methods and materials: In a prospective protocol investigating RP and cytokines, IL-1alpha and IL-6 values were analyzed by enzyme-linked immunosorbent assay from serial weekly blood samples of patients receiving chest radiation. We analyzed sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) over selected threshold values for both cytokines in the application to diagnostic testing.
Results: The average coefficient of variation was 51% of the weekly mean IL-1alpha level and 39% of the weekly mean IL-6 value. Interleukin 1alpha and IL-6 became positively correlated with time. Specificity for both cytokines was better than sensitivity. IL-6 globally outperformed IL-1alpha in predicting RP, with higher PPV and NPV.
Conclusions: Our data demonstrate the feasibility of applying IL-1alpha and IL-6 measurements of blood specimens to predict RP. Interleukin-6 measurements offer stronger positive predictive value than IL-1alpha. This application might be further explored in a larger sample of patients.