Temporal increases in the incidence of childhood solid tumors seen in Northwest England (1954-1998) are likely to be real.

Abstract

There has been speculation that increasing trends in incidence of childhood central nervous system tumors and infant neuroblastoma in the United States have been due to diagnostic improvements or reporting changes. To investigate whether or not such trends could be explained in this way in the U.K., the authors used population-based data from Northwest England to analyze incidence trends in childhood solid tumors. Cases were diagnosed during 1954-1998 and were grouped according to a morphology-based classification scheme. More than 95% of diagnoses were based on special histopathologic review. Tissue sections were retained, and diagnoses were rereviewed to ensure consistency in classification throughout the time period. Age-, gender- and period-specific incidence rates were calculated. Analyses were performed with chi-square tests and Poisson regression. There was an overall increase in the incidence of all childhood solid tumors of 0.9% each year. A temporal increase was found in childhood brain tumors characterized by, in particular, annual increases of 1% in pilocytic astrocytoma, 1% in primitive neuroectodermal tumors, and 2.3% in miscellaneous gliomas. The incidence of germ cell tumors increased at a rate of 2.6% each year. These increases could not be attributed to changes in diagnostic practice, and it is unlikely that the increases were due to changes in reporting practice. Further, the restriction of the increases to certain groups, with stable rates in others, argued against the changes being artifactual. The authors concluded that the increases in incidence were likely to be real.