Background: Background:Arterial thrombotic events (ATE) are important cause of noncancer-related deaths among patients with cancer. It is estimated that the prevalence of ATE among those patients is between 2-5%. However, data regarding acute myeloid leukemia (AML) related ATE are scarce and far less available than those related to venous thrombotic events.

Background:Background:Examination of central nervous system (CNS) involvement is not routine diagnostic in adult patients with acute myeloid leukemia (AML). Therefore, its impact on the disease course is not well defined. There are studies showing that CNS involvement in AML is associated with a worse outcome, whereas others did not confirm such impact on long-term survival.Aims: Aims: To determine the incidence of CNS involvement, its impact on the disease free and overall survival, and to define risk factors for CNS involvement. Methods:Methods: This single center, retrospective study involved 645 adult patients with nonpromyelocytic AML, diagnosed in period of 2013. and 2021. In patients with the presence of CNS symptoms, with increased leukocyte count (≥30x10 9 /L), FLT3 mutation, monocyte phenotype, CD56 positivity, a lumbar puncture was performed. All cerebrospinal fluid (CSF) samples were examined by flow cytometry (FCM). Treatment of CNS+ include intrathecal CT: cytarabine 100 mg. Assessment of remission of CNS+ was performed after 8 i.t. CT. The following parameters were estimated as risk factors for CNS+ at diagnosis of AML: age, WBC (<30x10 9 /L vs. ≥30x10 9 /L), ECOG PS, HCT CI score, elevated lactate dehydrogenase (LDH), leukemia-related parameters (cytogenetics (including ELN risk stratification), flow cytometry). The methods of descriptive and analytical statistics were used. Univariate and multivariate Cox Proportional Hazards models were used to identify risk factors. Results:Results: CNS involvement examination was performed in 272 patietns. A total of 55/272 (20.2%) patients had proven CNS involvement, while 217/272 (79.8%) were without neuroleukemia. Complete remission was achieved by 168/272 (61.7%) of patients, but there was no statistically significant difference between CNS positive and CNS negative patients (p=0.619). Patients with CNS involvement at diagnosis had a significantly higher frequency of hyperleukocytosis (≥30x10 9 /L), age ≤50 years, French-American-British M5 subtype, expression of CD56 and CD15 antigen. Multivariate analysis identified CD56+ as the most important risk factor for CNS+ at diagnosis in AML patients: p=0.003, HR 2.271; 95% confidental interval (CI)= 1.320-3.908. There were no statistically significant differences in 5-year overall survival and disease free survival between CNS positive and CNS negative patients. Summary/Conclusion:Summary/Conclusion: Our study showed a high incidence of CNS involvement in AML patients, compared to studies in which the incidence was significantly less (3.3%). Our study confirmed the accuracy of the factor we used to assess CNS involvement. There was no difference in the outcome between patients with CNS involvement and those without.