Biological Characterisation of High Risk CHildhood Cancer in Children, Adolescents and Young Adults (MICCHADO)

Inclusion Criteria: 1. Inclusion within 3 months after diagnosis 2. Availability of a cryopreserved tumour sample (primary and/or metastatic and/or lymph nodes) or peripheral blood or bone marrow samples (if invasion more than 30% of lymphoblasts) for leukaemias, obtained at the time of diagnosis during a routine procedure 3. Availability of a formalin-fixed paraffin-embedded (FFPE) tumour sample (primary and/or metastasis and/or lymph nodes), obtained at the time of diagnosis during a routine procedure (except for leukaemia patients) 4. Age: ≤ 25 years at diagnosis 5. Written patient informed consent, or parents or legal representative written informed consent and assent of the child and the adolescent 6. Compulsory affiliation to a social security scheme Additional inclusion criteria for the study: To avoid multiple sampling for children, adolescents and young adults with cancer, patients already included or to be included in a study with similar analyses and/or objectives might also be included in MICCHADO study and in this case, samples or data might be exchanged on a collaborative basis. Cohort 1: * High risk neuroblastoma: \- Any type of neuroblastoma with MYCN amplification, except INSS stage 1 \- Stage 4 neuroblastoma in children older than one year at diagnosis * High risk rhabdomyosarcoma: * Foxo1 rearrangement any stage; * and / or N1 ; * and / or metastatic rhabdomyosarcoma * High risk Ewing sarcoma: * Metastatic Ewing sarcoma family of tumours (ESFT) * Localised inoperable Ewing sarcoma with primary tumours ≥ 200 ml * High risk osteosarcoma: \- Metastatic osteosarcoma \- Localised inoperable osteosarcoma * High risk leukaemia: * Secondary acute myeloid leukaemia * Biphenotypic acute leukaemia Cohort 2: • Extra cerebral or cerebral high risk tumours including: * other metastatic sarcomas, * other rare high risk cancers, * high risk renal tumours with surgery after an initial chemotherapy * rhabdoid brain tumours (AT/RT) and extra cerebral rhabdoid tumours * high risk or metastatic cancers of unclear histological diagnosis • Lymphoblastic leukaemia with high MRD at Day 78 (time point 2) • Very high risk T-cells acute lymphoblastic leukaemia: * MRD ≥ 10-2 at the end of the induction ; * or MRD ≥ 10-3 at Day 78 Cohort 3: Children, adolescents and young adults, with low/intermediate risk cancers belonging to the following types: • Neuroblastoma: \- Localised, without MYCN amplification * Localised, INSS stage 1, with MYCN amplification * Stage 4s, in infants (younger than one year at diagnosis), without MYCN amplification • Rhabdomyosarcoma: * Localised, without Foxo1 rearrangement • ESFT: * All non-high risk localised ESFT • Osteosarcoma: * All non-high risk localised osteosarcoma Exclusion Criteria: Main non-inclusion Criteria common to all study cohorts: 1\) Age: patients \> 25 years old at diagnosis 2) Absence of patient or parents or legal representative written informed consent 3) Patient for whom follow-up by the investigating centre does not appear feasible