Chromosome karyotype of bone marrow and its clinical significance in the first diagnosis of neuroblastoma with bone marrow metastasis

Objective To summarize and analyze the results of chromosome karyotype in children with neuroblastoma (NB) with bone marrow metastasis at first diagnosis, and to discuss the clinical significance. Methods G-banding was applied to the analysis of chromosome karyotype of patients who were regularly treated in the Hematological and Oncology Center in Beijing Children′s Hospital from January 2015 to December 2017, and all the patients were followed up until December 31, 2018.Their clinical features and prognosis were analyzed. Results (1) There were 120 cases with bone marrow metastasis, including 74 boys and 46 girls, and 98 cases (81.7%) were ≥ 18 months.Among 60 cases with normal chromosome, 56 cases (93.3%) were in International Neuroblastoma Staging System(INSS)-Ⅳ phase, and 4 cases in INSS-Ⅳs phase; there were 2 low-risk (LR) cases, 9 intermediate-risk (MR) cases, and 49 high-risk (HR) cases (81.7%); 7 cases had MYCN gene amplifications.All 60 patients with chromosome abnormalities were in INSS-Ⅳ phase; there was 1 case in MR and 59 cases (98.3%) in HR; 14 cases had MYCN gene amplifications.(2) Among 60 children (50%) with chromosome abnormalities, 4 children had number abnormalities, 14 children had structural abnormalities, and 42 children had both number and structural chromosome abnormalities.Chromosome 21, 10, 11 deletions were the most common in number abnormalities; structural abnormalities involving 11q, 1p, 3p segments had a high incidence.(3) Seventeen cases of children with normal chromosome had tumor progression or recurrence during the 4 to 44-month follow-up period, and 31 cases of children with chromosome abnormalities had tumor progression or recurrence during the 2 to 42-month follow-up period.The 3-year overall survival rate and event-free survival rate of all children were 60.0% and 48.4%, respectively; children in the normal chromosome group had a 3-year overall survival rate of 74.2% and an event-free survival rate of 65.7%; the 3-year overall survival rate and event-free survival rate of children with chromosome abnormalities were 47.5% and 24.9%, respectively.Most children suffering from tumor progression or recurrence had chromosome 10 deletion, and abnormal structure of 11q, 1p, 2p segments. Conclusion The chromosomal abnormality rate of Nb children's tumor cells is high, but the repetition rate is low, and the individual difference is obvious.The deletion of chromosome 10, abnormal regional structure of 11q, 1p and 2p segments may be poor prognostic factors for NB.Chromosome karyotype analysis of bone marrow samples is feasible, which can provide a basis for more accurate risk stratification and treatment. Key words: Neuroblastoma; Bone marrow metastasis; Chromosome karyotype