Leukemia and lymphoma incidence in children in Alberta, Canada: a population-based 22-year retrospective study

There is a paucity of published literature on the epidemiology of childhood acute leukemias and lymphomas in Canada. This study was designed to describe children and youth (age <20 years) diagnosed with acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), Hodgkin lymphoma (HL), and non-Hodgkin lymphoma (NHL) in Alberta, Canada, during 22 fiscal years. The Alberta Cancer Registry was used to extract data all ALL, AML, HL, and NHL cases diagnosed between April 1, 1982, and March 31, 2004. Population data for Alberta were also obtained. Descriptive statistics and cluster detection tests were used. During 22 years, 525, 117, 257, and 111 children (total = 1010) were diagnosed with ALL, AML, HL, and NHL, respectively. The median ages at diagnosis were 4, 11, 16, and 12 years for ALL, AML, HL, and NHL, respectively. The majority were male for ALL (287/525, 55%), AML (64/117, 55%), and NHL (81/111, 73%), and female for HL (133/257, 52%). The crude rates per 100,000 children were variable, without significant trends, over time and for each diagnosis; the median annual rates, per 100,000 children, were 3.00 (ranging from 1.87 to 3.75) for ALL, 0.62 (ranging from 0.26 to 1.27) for AML, 1.42 (ranging from 0.76 to 2.67) for HL, and 0.54 (ranging from 0.24 to 1.40) for NHL. A few potential spatiotemporal clusters were identified. They are likely due to small number of cases and plausibly clinically insignificant. Overall, childhood leukemia and lymphoma rates in Alberta have remained relatively stable, with no clear epidemiological trends and no significant spatiotemporal clustering. Further investigations are warranted to see if such stability continues and if spatiotemporal patterns arise from longer studies and studies in larger geographic regions with a larger sample size, whilst analyzing for other causal/associated factors, individual susceptibilities, and disease outcomes.