An analysis of trends in mortality from malignant melanoma of the skin in Australia

Australian mortality rates from cutaneous malignant melanoma in successive periods from 1931 to 1977 have been examined with respect to geographic variation and trend with time and birth cohort. The age-standardized rates rose from 0.8/100,000 in males and 0.6/100,000 in females in 1931-34 to 4.2/100,000 and 2.5/100,000 in 1975-77. Mortality rates were highest in Queensland in the north of Australia and diminished on a gradient from the north to south of the country. An analysis designed to separate effects due to calendar year, birth cohort and age showed that virtually all the secular trend in rates could be explained by increases in successive birth cohorts, beginning as early as 1865 and stabilizing with the cohorts born around 1925 in women and 1935 in men. It is suggested that the cohort-based increase in mortality resulted from life-style changes occurring with successive generations. Its stabilization in recent birth cohorts, if persistent, suggests that the secular trend towards increasing total mortality from melanoma will also stabilize over the next 40 years.