Increasing incidence of childhood cancer: report of 20 years experience from the greater Delaware Valley Pediatric Tumor Registry.

As little is known about the aetiology of cancer in children, analysis of time trends may be useful. Recent data on time trends for paediatric cancers are very limited. We report here on trends in the incidence of 15 categories of cancer in children under 15 years of age from 1970 to 1989, using data from the Greater Delaware Valley Pediatric Tumor Registry in the US. Total cancer incidence increased 1% per year (P < 0.001). Neither acute lymphocytic leukaemia, acute myelocytic leukaemia, nor total leukaemia incidence changed significantly. In contrast, the incidence of central nervous system (CNS) tumours rose 2.7% per year (P < 0.001). All three subgroups of this category, glioma, primitive neuroectodermal tumor (PNET)/medulloblastoma, and other CNS tumours, showed increases. For glioma and PNET/medulloblastoma, trends differed by age, race, and/or gender. Among the other childhood cancers, significant increases were observed for non-Hodgkin lymphoma and neuroblastoma. For osteosarcoma and retinoblastoma, no overall change in incidence was observed, although decreases were observed in some age and race subgroups. The rise in CNS tumour incidence confirms previous reports from the US and Great Britain. The lack of change for acute lymphocytic leukaemia conflicts with other data from the US, but diagnostic changes appear to explain at least part of the discrepancy. The increase in neuroblastoma has also been observed in Great Britain. In contrast to our finding, investigators in the US and Great Britain have reported no rise in non-Hodgkin lymphoma. Analyses for more of the childhood cancers from other registries would aid in detecting and interpreting incidence trends in recent years.