Population based survival analysis of childhood cancer.

Abstract

Purpose: To assess the survival of children diagnosed with cancer between 1982 and 1988 using population based data. Subjects: 4715 cancer patients diagnosed with cancer prior to age twenty, between 1982-1988, as reported population based cancer registries. Mortality status (up to December 31, 1991) was ascertained by linking subjects to the Canadian mortality database. Actuarial survival rates and assessment of the role of covariates (ie. gender, age at diagnosis, year of diagnosis) on survival using the proportional hazards model. The five year survival rate of children diagnosed with a primary malignancy between 1982 and 1988 was 69%. Among those cancers examined, age at diagnosis was a significant prognostic factor for children diagnosed with leukaemia, neuroblastoma, astrocytoma, ependymoma, and rhabdomyosarcoma ($\rm p0.05$). Infants with leukaemia had a substantially poorer prognosis when compared to children diagnosed after age one. Conversely, those diagnosed with neuroblastoma prior to age one had a considerably improved chance of survival. After adjusting for age and year of diagnosis, females were found to have a markedly higher survival for acute lymphocytic leukaemia, and ependymomas ($\rm p0.05$). Improved survival was observed for children diagnosed more recently with acute lymphocytic leukaemia, acute non-lymphocytic leukaemia and Non-Hodgkin's lymphoma ($\rm p0.02$). There was evidence to suggest that survival also improved by year of diagnosis among children with fibrosarcoma ($\rm p=0.05$), Wilms' tumour ($\rm p=0.07$) and ovarian germ cell malignancies ($\rm p=0.06$). No significant trends in survival were observed for the other forms of childhood cancer examined. Geographical variations in survival were assessed for children diagnosed with either acute lymphocytic leukaemia, an astrocytoma or Hodgkin's disease. The survival rates among children diagnosed with acute lymphocytic leukaemia or astrocytoma in British Columbia between 1987 and 1988, were found to be significantly higher when compared to the remainder of the cohort ($\rm p0.05$).