The changing pattern of cancer mortality in South Africa, 1949-1979.

The first paper in this series was published in 1975 and covered the period 1949 - 1969 for whites, coloureds and Asians in South Africa. This period is now extended to 30 years, from 1949 to 1979 inclusive, and includes data for urban blacks from 33 selected urban areas for the period 1968 - 1977. This information was superseded by data for all blacks, both rural and urban, in 1978. As this is available only for 2 years, the data are not included in this series, and all mention of blacks indicates information on urban blacks only. It is reassuring to know that mortality and geographical data for urban and rural blacks can now be separated from each other for comparative purposes, and that, in the future, transitional trends due to such striking phenomena as migratory labour and emigration to industrial areas can now be determined by the year. Finally, instead of expressing mortality rates per 100 000 of the population, a new method called the "cumulative rate or risk' is used, which is carefully defined. Changes in cancer patterns in all four major population groups are reflected graphically over the period 1949 - 1979 (blacks since 1968) by this method, and trends over this long period are discussed in terms of the frequency of cancers within each group, prognosis, aetiological factors and other related aspects.