A comparison of trends in melanoma mortality in New Zealand and Australia: the two countries with the highest melanoma incidence and mortality in the world

Abstract

BackgroundNew Zealand and Australia have the highest incidence and mortality rates from cutaneous melanoma in the world. The predominantly fair-skinned New Zealanders and Australians both enjoy sun, tanned skin and the outdoors, and differences in these activities among generations have been important determinants of trends in melanoma mortality.We examined whether New Zealand trends in melanoma mortality mirror those in Australia, through detailed comparison of the trends in both countries from 1968 to 2007.MethodsFive-year age-specific and age-standardised mortality rates were calculated for each country for 5-year time periods. Tests for trends in age-specific rates were performed using the Mantel-Haenszel extension chi-square test. The age-adjusted mortality rate ratios for New Zealand/Australia were plotted against period of death to show relative changes in mortality over time. Age-specific mortality rates were plotted against period and the median year of birth to illustrate age-group and birth cohort effects. To compare the mortality of birth cohorts, age-adjusted melanoma mortality rate ratios were calculated for the birth cohorts in the quin-quennial tables of mortality rates.ResultsThe age-standardised mortality rate for melanoma increased in both sexes in New Zealand and Australia from 1968 to 2007, but the increase was greater in New Zealanders and women in particular. There was evidence of recent significant decreases in mortality in younger Australians and less so in New Zealand women aged under 45 years. Mortality from melanoma increased in successive generations born from about 1893 to 1918. In Australia, a decline in mortality started for generations born from about 1958 but in New Zealand there is possibly a decrease only in generations born since 1968.ConclusionsMortality trends in New Zealand and Australia are discrepant. It is too early to know if the pattern in mortality rates in New Zealand is simply a delayed response to melanoma control activities compared with Australia, whereby we can expect the same downward trend in similar age groups in the next few years. Specific research is needed to better understand and control the increases in mortality and thickness of melanoma in New Zealand.

Epidemiology of Melanoma

“…This trend is seen among most high-risk populations, including individuals in Australia and New Zealand (23,65), and Northern Europe (28,30). Incidence in the United States, however, peaks at the sixth decade of life (6).…”

“…Melanoma mortality trends are variable and, as with incidence, are influenced by geography, ethnicity, age, and sex (11,19,65,67,68,94,95). Melanoma mortality rates have marginally increased among fair-skinned populations (19,32,68,96).…”

Excision margins and sentinel lymph node status as prognostic factors in thick melanoma of the head and neck: A retrospective analysis

“…It is estimated that, in 2015 in Australia, 12,960 new cases of melanoma will be diagnosed, making up 10.2% of all new cancer diagnoses and a projected 1675 Australians will die from the disease. 2 In the United States, the estimated number of melanoma diagnoses in 2013 was 76,690 with 9840 deaths. 3 Up to 25% of all cutaneous melanomas are located in the head and neck.…”

Cutaneous malignant melanoma show geographic and socioeconomic disparities in stage at diagnosis and excess mortality

“…In Sweden, the total number of melanomas has increased by nearly 75% during the last decade, corresponding to a 5% annually increased incidence. Australia has been a frontrunner in melanoma prevention and a decline in melanoma mortality on the population level has been demonstrated for individuals born after about 1958 [2]. Several other countries, including New Zealand, the US, Canada and Norway, have succeeded in halting the incidence of melanoma in younger age groups, primarily thorough awareness programs related to the risk associated with sun exposure [1].…”