Breast cancer mortality trends in Australia: 1921 to 1994

To analyse breast cancer mortality trends in Australia and to see if mammographic screening has yet led to a reduction in mortality.

Retrospective analysis of trends in mortality rates from breast cancer in Australian women between 1921 and 1994, and in potentially explanatory variables such as fertility, body size, age at menarche, and screening.

Changes in breast cancer mortality in Australian women could not be explained by chance variation alone. Mortality rose steadily (average annual increase, 1.0%) to 1940-1944, fell to the 1960s and early 1970s, and rose (average annual increase, 0.3%) to the late 1980s. Between 1985-1989 and 1990-1994, breast cancer mortality fell by 3.2% in women 50-69 years of age (the target age group for mammographic screening) and by 4.2% in women 25-49 years of age. There was almost on change (-0.2%) in breast cancer mortality in older women in this period. The proportion of women screened in all age groups increased substantially between 1988 and 1994; nearly 65% of women in the target age group had had at least one mammogram by 1994. Decreases in fertility were followed by increases in mortality, and vice versa.

Trends in breast cancer mortality have probably been influenced by changing fertility, nutrition and body-size increases among Australian women. Improvements in stage at diagnosis and treatment have probably moderated the upwards pressure on mortality caused by an increasing incidence. Recent falls in mortality could be expected to continue as more women participate in the mammographic screening program. This trend should be more clearly evident in the second half of the 1990s.