Acute Disease|Algorithms|Biomarkers, Tumor|Child|Child, Preschool|Gene Expression Profiling|Gene Expression Regulation, Neoplastic|Humans|Infant|Infant, Newborn|Leukemia, Myeloid|Lymphoma, Non-Hodgkin|Models, Genetic|Models, Statistical|Neoplasms|Neuroblastoma|Oligonucleotide Array Sequence Analysis|Precursor Cell Lymphoblastic Leukemia-Lymphoma|Principal Component Analysis|Rhabdomyosarcoma|Sarcoma, Ewing