Trends in International Incidence of Pediatric Cancers in Children Under 5 Years of Age: 1988-2012

Background: Pediatric cancer incidence has been steadily increasing over the last several decades with the largest increases reported in infants. Few evaluations have looked at international pediatric cancer incidence trends in the youngest children. The aim of this analysis was to evaluate trends in cancer incidence in children under 5 years of age, overall and by type, using data from Cancer Incidence in 5 Continents (CI5) from 1988 to 2012 (CI5 volumes VII-XI).

Methods: Rates of cancers in children ages 0-4 years were extracted from registries available in CI5 from 1988 to 2012. To overcome small numbers in individual registries, numerators and denominators were aggregated within regions corresponding to the United Nations' geoscheme. Average annual percent change (AAPC) was estimated using Poisson regression. Robust standard errors were used in all models to correct for overdispersion in some regions, and 95% Wald confidence intervals and P values were reported. The top five cancers by increasing AAPC were ranked within each region.

Results: Overall, in children under 5 years, increasing incidence was seen in multiple regions for acute lymphoblastic leukemia, acute myeloid leukemia, ependymal tumors, neuroblastoma, and hepatoblastoma. Hepatoblastoma had the largest AAPC in 11 out of 15 regions and showed an increase in all regions except southern Asia. Astrocytic tumors were the only cancer that decreased over the time period.

Conclusions: We evaluated 25 years of cancer incidence in children ages 0-4 years and observed increases in incidence for hepatoblastoma, leukemia, neuroblastoma, and ependymal tumors. Further etiologic evaluation will be required to explain these increases in incidence.