Temporal trends in incidence of childhood cancer in Switzerland, 1985-2014.

Background: Incidence of childhood cancer increased in most countries worldwide, but reasons are unclear. This study investigates trends of childhood cancer incidence in Switzerland from 1985 to 2014.
Methods: We extracted data on all childhood cancer cases diagnosed at ages 0-14 years in Switzerland from the Swiss Childhood Cancer Registry. We included ICCC-3 main groups I-XII and calculated age-standardised, cumulative, and age-specific incidence for different diagnostic groups. We analysed trends of annual age-standardised incidence using JoinPoint regression models.
Results: Over the study period from 1985 to 2014, 5104 of 5486 cancer diagnoses (93%) were microscopically verified. The proportion of children treated in paediatric cancer centres increased from 84% during 1985-1994 to 93% in 1995-2004 and 98% in 2005-2014 (p < 0.001). Using the World standard population, age-standardised incidence was 143 in 1985-1994, 154 in 1995-2004, and 162 per million in 2005-2014. Incidence increased by 0.7% (95% confidence interval (CI) 0.5; 1.0) per year for all cancers from 1985 to 2014, 0.8% (95% CI 0.2%-1.4%) for leukaemias over the same period, 3.0% (95% CI 0.2%-1.4%) for CNS tumours during 1985-2002, and 3.8% (95% CI 1.7%-6.0%) for epithelial neoplasms and melanomas over the period 1985-2014.
Conclusion: Trends in incidence were driven mostly by increases among leukaemias and CNS tumours. For CNS tumours, observed trends may be explained at least partially by diagnostic changes and improved registration. For leukaemias, rising incidence may be real and due to risk factors that experience similar increases in trends.
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