Comparing melanoma risk in similar populations across different latitudes

Comparing melanoma risk in similar populations across different latitudes

20 October 2017

People at high risk of developing melanoma are often identified by clearly visible characteristics like fair skin, red or blonde hair, blue eyes and moles (called nevi). These factors have been consistently associated with melanoma risk, but the strength of these associations may differ by the latitude of where they live, patient characteristics (e.g. age or gender) and how the study was conducted.

Associate Professor Anne Cust, epidemiologist at Melanoma Institute Australia and The University of Sydney, and her team performed a comprehensive analysis of these associations with melanoma risk in two population-based studies – one in Australia and another in Leeds, UK. These two countries have similar ancestry but different levels of ambient sun exposure because of the very different latitudes.

“We found that Australians have three times higher mole counts on average than those living in the UK, which contributes to Australia’s higher burden of melanoma,” said A/Prof Cust.

The strength of associations with melanoma risk was similar for both populations when based on self-reported measures but was higher for Leeds than Australia when based on clinically assessed moles.

“We also found some differences according to body site of mole counts and by gender – for example, mole counts on the upper and lower limbs were most predictive of melanoma risk, and relatively high mole counts on the head and neck were associated with a stronger risk for melanoma for women than men,” she said.

They concluded that classifying people at high risk of melanoma based on their number of moles should ideally take into account their country of residence, gender and the body site on which the mole counts are measured.

“These findings are clinically relevant and topical to the ongoing discussions regarding how best to identify and screen people at high risk of melanoma,” said A/Prof Cust.

The research is being presented at the World Congress of Melanoma in Brisbane today and a research paper is currently under review describing these findings.