STUDY OF CANCER MORTALITY IN ENGLAND AND WALES USING BIRTH-STANDARDIZED POPULATIONS BY

It is well recognized that, in estimating secular trends ofcancer mortality, the changing age-structure of the population must be taken into account. In England and Wales the proportion of the population in the older age groups has been steadily increasing; for example, in 1956-59, 53 per cent. of the female population were over 35 years of age, as compared with 41 per cent. in 1921-25. This increase is attri-butable to two causes: first, the falling mortality in lower age groups consequent upon improvements in public health and the treatment of infectious diseases; secondly, the decline in the birth-rate which took place between 1901 and 1931. To allow for these changes in age-structure, it is customary to calculate mortality indices on a stan