Significance of Interleukin-6 (IL-6) and C-reactive Protein (CRP) in Children and Young Adults With Febrile Neutropenia During Chemotherapy for Cancer

Abstract

We evaluated the usefulness of interleukin-6 (IL-6) and C-reactive protein (CRP) at the onset of febrile neutropenia and 72 hours later, in identifying risk groups and assessing response to antibiotic therapy. All episodes of febrile neutropenia were divided in 3 study groups-microbiologically documented infection (MDI), clinically documented infection (CDI), and fever of unknown origin (FUO). Three outcome groups were defined as those responding to first-line antibiotics (R1), those responding to second-line antibiotics (R2), and those requiring antifungal therapy (RAF). Median values of IL-6 and CRP were compared between the groups. There were 57 episodes of febrile neutropenia among 26 patients younger than 25 years during 1 year of study period. On day 1, median IL-6 level was significantly lower in FUO group compared with CDI+MDI groups combined (P < 0.001). Rise in CRP on day 3 was highly significant to differentiate MDI group from other 2 groups (P < 0.001). The CRP also increased significantly on day 3 in RAF (P < 0.001) and R2 (P = 0.002) groups than in R1 group. Low level of IL-6 may help differentiate patients with FUO from those with documented infections. A rising CRP is indicative of serious infection.