Epidemiology of pediatric hematological malignancies in Kazakhstan: Data from Unified National Electronic Healthcare System 2014-2021.

We aimed to describe incidence and all-cause mortality of hematological pediatric malignancies (leukemia and lymphomas) in Kazakhstan based on nationwide large-scale healthcare data from the Unified National Electronic Healthcare System (UNEHS) for the 2014-2021 year period. The cohort included data of patients less than 18 years old with the diagnosis of hematological malignancies registered in the UNEHS (inpatient and outpatient registries) for the year period 2014-2021. Descriptive statistics were conducted to indicate socio-demographic characteristics of the cohort. Incidence and all-cause mortality were calculated per 100,000 population. Cox proportional hazard regression analysis was performed to investigate the association between determinants with the all-cause mortality. The total cohort consisted of 3357 children with leukemia and 1474 children with lymphomas. The mean age at diagnosis of leukemia and lymphomas was 7.3 ± 4.7 and 9.9 ± 4.9 years, respectively. The incidence rate of hematological malignancies was 6.8 per 100,000 in 2021. Patients with ALL had a higher incidence rate than patients with AML (3.4 and 1.2 per 100,000 in 2021, respectively). The incidence rate of HL and NHL was relatively similar which varied from 0.6 to 2.6 per 100,000 in 2014-2021. All-cause mortality of pediatric hematological malignancies varied from 1.1 to 1.5 per 100,000 in 2014-2021, with the peak in 2016 (1.7 per 100,000). Younger age is significantly associated with increased risk of all-cause mortality in children with AML. CONCUSION: Patients with ALL had a higher incidence rate than patients with AML. The incidence rate of HL and NHL was relatively similar. All-cause mortality rates for leukemia and lymphomas were quite stable during the study period. Younger age is significantly associated with increased all-cause mortality among AML patients. However, there is no significant association of age with all-cause mortality among ALL, HL and NHL. In order to obtain more reliable data and analysis on pediatric (hematological) malignancies, specific registries for childhood tumors (including detailed information on relapses, treatments, short and long-term side effects, and specific death causes) should be implemented. WHAT IS KNOWN: • Leukemias and lymphomas together account for around 45% of all pediatric malignancies. • Lymphoma accounts for 12% of all childhood malignancies; non-Hodgkin's lymphomas (NHL) are more frequent than Hodgkin's lymphomas (HL). WHAT IS NEW: • The incidence rate of ALL was higher than the incidence rate of AML throughout the whole study period, whereas all-cause mortality of ALL and AML was quite stable. • According to Cox PH analysis, younger age (0-5 years old) was associated with a higher risk of death among AML children compared to older children, and no significant association of age was observed with all-cause mortality among ALL and lymphomas.