title: Interleukin-6 and soluble interleukin-6 receptor levels as markers of disease extent and prognosis in neuroblastoma.
abstract: OBJECTIVE
  To explore the relationships between interleukin-6 (IL-6) and soluble IL-6 receptor (sIL-6R) levels and disease extent and clinical outcome in childhood neuroblastoma.
  
  
  METHODS
  Pretreatment peripheral blood (PB; n=53) and bone marrow (n=18) samples from patients with neuroblastoma were assayed by ELISA for IL-6 and sIL-6R. PB values were compared with healthy pediatric controls (n=28).
  
  
  RESULTS
  PB IL-6 levels were significantly elevated in patients with high-risk disease compared with those with low and intermediate risk disease (23.9 versus 4.3 pg/mL; P<0.001) and the normal control group (23.9 versus 3.3 pg/mL; P<0.001). Similarly, bone marrow IL-6 levels were higher in high-risk patients when compared with low- and intermediate-risk patients (15 versus 0 pg/mL; P<0.02). Other factors correlated with higher IL-6 levels were age of >18 months, bony metastases, and unfavorable histology. sIL-6R levels were not significantly correlated with disease stage. Patients with detectable PB IL-6 at diagnosis had significantly lower event-free survival rates (P<0.008). sIL-6R levels <2.5 x 10(4) pg/mL were also associated with a significantly worse event-free survival (P=0.016).
  
  
  CONCLUSIONS
  Elevated PB IL-6 levels correlated with features of high-risk neuroblastoma and poor prognosis in this population. Decreased PB sIL-6R levels correlated with the presence of metastatic disease. Further study of these markers in children with neuroblastoma seems warranted.
authors.affiliation: Department of Pediatrics, Texas Children's Cancer Center, Baylor College of Medicine, Houston, Texas 77030, USA. egler@bcm.edu
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Egler
authors.forename: Susan M
authors.initials: SM
authors.lastname: Burlingame
authors.forename: Jed G
authors.initials: JG
authors.lastname: Nuchtern
authors.forename: Heidi V
authors.initials: HV
authors.lastname: Russell
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D001853:Bone Marrow / Q000737:chemistry; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007223:Infant; D015850:Interleukin-6 / Q000032:analysis* / Q000097:blood; D008297:Male; D009447:Neuroblastoma / Q000175:diagnosis / Q000378:metabolism*; D011379:Prognosis; D019947:Receptors, Interleukin-6 / Q000032:analysis* / Q000097:blood
chemical_list: D014408:Biomarkers, Tumor; D015850:Interleukin-6; D019947:Receptors, Interleukin-6