Area-based differentials in childhood cancer incidence in Australia, 1996-2006.

BACKGROUND International studies examining the association between the incidence of childhood cancer and characteristics of the area in which the patient lives have generally reported inconsistent patterns. Area-based differentials in childhood cancer throughout Australia have not been previously published at a national level. PROCEDURE Population-based information from the Australian Paediatric Cancer Registry was used to identify all children aged 0- to 14-years old diagnosed with invasive cancer or intracranial and intraspinal tumors of benign or uncertain behavior between 1996 and 2006. Age-standardized incidence rates per million children per year and the corresponding incidence rate ratios were calculated, categorized by remoteness of residence and an area-based index of socioeconomic disadvantage. Results were also stratified by the most common types of childhood cancer. RESULTS There was a significant, decreasing gradient in the incidence of childhood cancer as remoteness of residence increased. Children living in remote or very remote areas were 21% less likely to be diagnosed with cancer compared to children in major cities, mainly due to differences in the incidence of leukemias and lymphomas. This differential was no longer significant when only non-Indigenous children were considered. No clear relationship was found between incidence and socioeconomic status (SES) in contrast to similar earlier studies. CONCLUSIONS The findings by remoteness of residence are consistent with the lower incidence rates of cancer that are typically associated with Indigenous Australians. There is also a suggestion that the etiological factors associated with childhood leukemia and SES may have altered over time.