Risk indicators in childhood malignancies.

A series of 972 childhood malignancies was compared with a control series of healthy children matched for date and place of birth. Several variables were tested for possible aetiological significance. The information was obtained from the Finnish Cancer Registry and from the antenatal records of the mothers. No significant associations were found between the various types of malignancies and the variables studied. In the group consisting of all malignancies, a risk ratio of 2.0 could be significantly excluded for most variables. In the leukaemia group, both pelvic X-ray and polio vaccination were associated with slightly elevated risk ratios, but the differences between this group and the match controls were not statistically significant. BCG vaccination was performed during the perinatal period in 90% of the children, but the proportion was the same in the study and control groups, and hence the hypothesis that this vaccination confers protection was not supported. The information is considered prospective and relatively reliable, and the authors suggest that these data may be useful when more extensive series are compiled from various sources.