Predictive value of PCT and IL-6 for bacterial infection in children with cancer and febrile neutropenia

Purpose Only a third of children with cancer and febrile neutropenia (FN) have a proven bacterial infection; nevertheless, most children are hospitalized and treated with intravenous antibiotics. Several biomarkers have been proposed as predictive markers for bacterial infection in this population. We aimed to evaluate the role of interleukin-6 (IL-6) and procalcitonin (PCT) in diagnosing bacterial infection in children with cancer and FN. Methods The study population was derived from a prospective database (2006-2013, IL-8 study) comprising children with cancer who presented with FN. From stored plasma samples (taken at admission and/or at 12-24 h), we determined the PCT and IL-6 levels. Consequently, we explored their relation with the presence of bacterial infection (positive blood culture, radiologically documented infection or clinical bacterial focus). We predefined cutoff values at 60 ng/L for IL-6 and 0.25 ng/mL for PCT. Results Seventy-seven FN episodes in 55 children with cancer were included. In 18 episodes (23.4%), a bacterial infection was documented. Both at presentation and after 12-24 h, median values of IL-6 and PCT were significantly higher in patients with a bacterial infection compared to patients without a bacterial infection. With both biomarkers above cutoff values, sensitivity was 93% (with either one, this was even 100%). The identified group at low risk for bacterial infection comprised 41% of the population. Conclusion PCT and IL-6 are promising markers in identifying bacterial infection in children with cancer and FN. In a subsequent project, we will incorporate these biomarkers in a risk assessment model that we will test prospectively in a clinical trial.