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Age-standardised mortality rates for breast cancer were examined for 20 countries in Europe, North America, Australia and New Zealand from 1950 to 1992 and age-birth cohort and age-period of death models were fitted to the data. Breast cancer mortality rates generally increased in the earlier decades, but more recently rates have levelled off or begun to decline in most countries. Only in 4 of the 20 countries studied, Belgium, Hungary, Poland and Spain, was there no evidence of a decline or leveling off or mortality in recent birth cohorts or in recent years. In the other countries the decline in mortality appeared to be in part due to birth cohort effects and in part due to period effects. The birth cohort effects were suggestive of a decline in breast cancer rates among women born after about 1920 and were evident in many countries especially Canada, The Netherlands, The United Kingdom and the United States. The decline in mortality in women born after 1920 appeared to be in part related to a reduction in childlessness and a reduction in age at first birth in those generations. As well as the birth cohort effects, there was some evidence of a recent overall decline in mortality rates in several countries, e.g. Austria, FRG, Greece and the UK, and this may be due to an increase in survival resulting from improved management and treatment of women with breast cancer.

The overall incidence of and mortality from cervical cancer has declined in western countries and in most developing countries. In women under 40 years of age, however, mortality rates are levelling off or increasing in most countries. The earliest and most marked increases in young women occurred in England and Wales, Scotland, Ireland, New Zealand and Australia. Mortality rates in young women from eastern European countries began to increase later than in the UK, but the increases are of concern because baseline mortality rates are high in these countries. The reasons for the overall decline in cervical cancer are largely unknown but appear to be linked to improvements in the general standard of living. The increases in young women may well be due to the increasing prevalence of HPV infection. Screening for cervical cancer has undoubtedly led to a decline in cervical cancer incidence and mortality in many countries, but its contribution to the trends is difficult to assess without further information.