Antenatal irradiation and childhood cancer: causation or coincidence?

A re-analysis of published data from the Oxford Childhood Cancer Survey shows that the frequency of leukaemia and of solid cancers in childhood is greater following antenatal x-radiography, not only in singleton births but also in monozygotic and dizygotic twins. The radiography rate was 10% in singletons and 55% in twins. A similar excess of leukaemia and of solid cancers in the x-rayed with such different rates of radiography is strong evidence for irradiation as the cause. The low observed frequency of malignant disease in Japanese bomb survivors exposed in utero may not be in serious conflict with this conclusion, as has been supposed.