Incidence patterns and temporal trends of childhood cancer in Germany, 1980-2019: Forty years of childhood cancer registration in Germany.

Comparing incidence patterns over time and between populations stimulates aetiological research and informs health policy. With this report, we provide the first comprehensive assessment and interpretation of 40 years of childhood cancer registration data and observed incidence patterns and time trends in Germany. We identified all incident childhood cancer cases diagnosed before the age of 15 years between 1980 and 2019 from the German Childhood Cancer Registry (N = 65,163) and examined incidence patterns and temporal trends. Over the entire period (1980-2019), boys were more frequently diagnosed than girls, children aged <5 years had the highest age-specific incidence rates and age-standardised incidence rates (ASR) were highest for leukaemias and CNS tumours. Trend analyses indicated a statistically significant increase in ASRs for childhood cancer overall (from 122.8/million in 1980-1989 to 173.4/million in 2010-2019) as well as across diagnostic groups and age groups. The steepest increase (on average 4.9% per annum for all cancer diagnoses combined) occurred in the initial years of registration (1980-1987), mostly driven by the sharp increase in the reporting of CNS tumours diagnoses, soft tissue sarcoma and germ cell tumours. Since the 1990s, temporal patterns were more heterogeneous across diagnostic groups; yet overall, less pronounced than during the build-up phase of the registry. Various factors have influenced the observed incidence patterns in Germany over the 40-year registration period. The steep increase in ASRs during the early years is primarily attributable to improvements in case reporting and registration. Explanations for the more recent temporal patterns remain speculative.