Background/aim Haematological malignancies are the most common cancer in people under age of 19 years. Moreover, in Belarus possible health consequences of radiation exposure among young groups of population are of special concern. The objective was to test for time trends in leukaemia and lymphoma in children and adolescents.

Methods Data on cases of acute lymphoblastic leukaemia (ALL), acute myeloid leukaemia (AML), Hodgkin lymphoma (HL), and non-Hodgkin lymphoma (NHL) diagnosed during 25 year period (1990–2014) were obtained from National Cancer Registry. Crude rates and cumulative risk were computed for lung cancer overall and by gender. Annual percent change (APC) and 95% confidence intervals (CIs) were estimated by linear regression to characterise trends in incidence rates over time for the overall population, by gender, by age group, and by age group within gender.

Results During 1990–2014, 4056 incident cases were diagnosed in children and adolescents. More cases were reported in males (2305) than females (1751). During this period, the average crude rate was 6.48 per 100 000 population without significant trends (APC 1.12%; CI: −0.69÷2.97). In males, average crude rate was 7.15, in females – 5.76.

The rates for ALL, AML, HL and NHL in males were stable with no significant trends. In females were observed significant increase for ALL (APC 1.98%; CI: 0.61÷3.36) and decline for NHL (APC −3.94%; CI: −6.73÷−1.08). When age subgroups were examined, the highest upward trend was observed for ALL in female age group 0–4 years old (APC 2.9%; CI: 1.2÷4.7) with even more expressed tendency in 2005–2014 (APC 12.3%; CI: 5.8÷19.1).

Conclusion Childhood leukaemia and lymphoma rates in Belarus have remained relatively stable, except the ALL in females. Further investigations are necessary to analyse for causal factors and individual susceptibility. Analysing time trends of cancer incidence could be useful to generate some new hypotheses for etiological researches.