Cytogenetic landscape aberrations in paediatric acute lymphoblastic leukaemia - a polish paediatric population treated according to ALL-IC BFM 2009 protocol.

Genetic findings are important independent prognostic factors in childhood acute lymphoblastic leukaemia (ALL). This study presents cytogenetic data correlated with clinical factors of 1337 patients aged 1-18 years with newly diagnosed ALL treated between 2011 and 2018 under the Polish ALL IC-BFM 2009 therapeutic protocol. Overall survival (OS) for children with B-cell ALL was 95.58% at 5 years, while OS for children with T-cell ALL was 80.43% (p < 0.001). The event-free survival (EFS) rates were 86.69% and 72.92%, respectively, and the difference was also statistically significant (p < 0.001). The most common karyotypes observed were normal in 31.79% (n = 425) and high hyperdiploidy (HeH) in 18.4% (n = 246). Two aberrations were associated with a good prognosis in patients with B-cell ALL: ETV6::RUNX1 (OS = 98.47% and EFS 92.75%) and high hyperdiploidy (OS = 97.52% and EFS = 92.5%). Patients with low hyperdiploidy as well as patients with BCR::ABL1 aberration (OS = 73.05%, EFS = 73.05%) indicated a trend towards worse results (OS = 92.29%, EFS = 81.21%). Death and relapse rates were significantly higher in HeH patients without trisomy 17 and 18 compared to those with double trisomy 17 and 18 (p = 0.013). Our study advocates, cytogenetic testing remains an important tool in the diagnosis of paediatric patients with ALL IC-BFM 2009 protocol, as well as it shows that cytogenetic testing's use for treatment stratification improved the outcome of children with ALL in Polish paediatric onco-haematology centres.