Australia’s population diversity may be impacting our melanoma rates

10th September 2024
Professor David Whiteman

3 min read

Researchers from QIMR Berghofer have found that declining melanoma rates among young Australians have been influenced by the country’s increasingly diverse population and more varied skin tones.

Cutaneous melanoma, a malignant neoplasm of melanocytes, is primarily caused by exposure to ultraviolet (UV) radiation from the sun. Melanocytes produce melanin, the ‘tanning’ pigment that protects other skin cells from the hazards of ultraviolet radiation, and which is primarily responsible for skin colour. The incidence of melanoma varies widely across populations, and is highest in populations with a large proportion of people with European ancestry whose fair skin produces very little melanin. People of African, Asian, Pacific Island, or Aboriginal or Torres Strait Islander descent typically have much higher levels of protective melanin in their skin, resulting in darker skin tones and a much lower risk of developing melanoma.

Historically, the Australian population has experienced very high rates of melanoma due to our proximity to the equator and the historical composition of our composition, which in previous decades featured a very high proportion of people with European ancestry. In response to high and rising skin cancer rates through the 1960s and 1970s, skin cancer prevention campaigns were first initiated in the very early 1980s and have continued with broad reach since that time. The aim of those campaigns was to increase awareness about the dangers of excessive sun exposure and thereby reduce sun exposure in the population.

Recently, declines in melanoma incidence have been observed among younger generations of Australians (although rates have been rising among older Australians). However, melanoma is the most common cancer diagnosed in young people aged 15 to 39.

” Melanoma incidence has risen steeply over time in people over 50, but has fallen steadily among young Australians “
Professor David Whiteman

At first, it seemed obvious that the falling melanoma rates recently observed among young Australians must be attributable to the success of the last four decades of skin cancer prevention campaigns. However, several commentators have pointed out that analyses of melanoma trends in the total population failed to account for population diversity, whereby an increasing proportion of Australians trace their heritage to Africa, Asia or the Pacific and have low ancestral risk for melanoma.

Thus, the aim of this study was to investigate how much of the observed decline in melanoma rates among young Australians was due to population diversity, and how much might be explained by prevention campaigns or other factors.

Detailed census data was used from 2006, 2011, 2016 and 2021 to estimate the numbers of Australians whose ancestry placed them at low, moderate, or high risk of melanoma. This was done for each of 14 age groups (from less than 10 years to over 85 years), and then used known melanoma rates for the different ancestral risk groups to estimate how many Australians in each group developed melanoma in each year.

We found that between 2006 and 2021, the estimated proportion of the Australian population at high risk of melanoma (i.e. those with predominantly European ancestry) declined from 85% to 71%, while the proportion of the population at low or moderate risk for melanoma almost doubled from 15% to 29%.

We estimated that more than 95% of melanomas that occurred in Australia in that time period arose in the high risk group. Our analyses confirmed that melanoma incidence has been falling among young Australians overall (as was already known), but we also showed that rates were falling even among those with high risk (i.e. mostly European) ancestry. Interestingly, when we looked at melanoma trends among young people with high risk ancestry in other countries such as New Zealand and the United States, we saw trends of declining melanoma rates similar to Australia. Notably, young people in New Zealand and the United States have had much less exposure to skin cancer prevention campaigns than young people in Australia, suggesting that skin cancer prevention campaigns are unlikely to have driven down melanoma rates as much as we thought.

One likely explanation for the decline in melanoma rates observed among young people in Australia, New Zealand, and the United States is that global changes in lifestyle have led to lower levels of sun exposure compared with sun exposure received by earlier generations. For example, young people around the world now have higher levels of screen time and reduced outdoor play, both of which lead to lower levels of sun exposure.

So, while skin cancer rates are falling among younger Australians, the reasons are complex and relate to increasing population diversity, skin cancer prevention campaigns, and broader societal changes. Nevertheless, almost every case of melanoma is preventable, at least in theory, so we must continue efforts to promote sun-safe behaviours and help the next generations avoid the skin cancer epidemic that has befallen previous generations.

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Professor David Whiteman is a medical epidemiologist with a special interest in the causes, control and prevention of cancer.

Whiteman DC, Neale RE, Baade P, Olsen CM, Pandeya N. Changes in the incidence of melanoma in Australia, 2006-2021, by age group and ancestry: a modelling study. Med J Aust. 2024 Sep 2;221(5):251-257.