According to a commentary, these data reinforce the notion that the slow but steady increase in the incidence of many childhood cancers reported since the 1970s is real, and that it is particularly notable for leukaemia. It notes that epidemiological studies so far have not identified clear risk factors for childhood cancer, therefore, hypotheses for reasons underlying the increasing cancer incidence in children remain largely speculative. However, relating the data to the significant changes in environmental, living, socioeconomic, and public health conditions in European countries after second world war might provide clues as to the nature of these reasons.