Significance of tumor biology compared to metastatic pattern (INSS 4 versus 4s) and age for prognosis of neuroblastoma less than 18 months of age

10010 Background: Neuroblastoma is a heterogeneous disease with variability in outcome among different risk groups. Historically, INSS stage 4s neuroblastoma (age less than 12 months, stage 1 or 2 primary tumor with metastases limited to liver, skin and bone marrow) has a more favorable outcome than infant stage 4 disease. The aim was to determine if metastatic pattern (4 vs 4s) predicted favorable prognosis in infants < 12 months or in toddlers aged 12–18 months when stratifying by biology. Methods: Outcome was analyzed by log rank tests and Cox models for 656 infants with stage 4s neuroblastoma and 1,019 stage 4 patients < 18 months of age in the International Neuroblastoma Risk Group database (n=8,800). Prognostic factors (tumor ploidy, histology, grade, MKI, LDH, MYCN, 11q, 1p, primary site) were tested for association with age/stage subgroups (Fisher's exact test) and in Cox models. Results: MYCNamplification, 1p aberration, diploidy, and high MKI and LDH were more frequent in infant stage 4 than inf...