Melanoma scourge may need more than slip, slop, slap
Doubt has been cast over the effectiveness of sun protection campaigns amid evidence that the incidence of melanoma is rising among young people most at risk of developing skin cancer.
Although there was a massive 325 per cent increase in the number of melanomas removed each year between 1982 and 2009, a number of studies have claimed that the incidence of melanoma among young people is decreasing as a result of public health campaigns such as the well-known slip, slop, slap SunSmart campaign.
But, in a study published in the journal Acta Dermato-Venereologica, Melbourne-based dermatologist Dr Douglas Czarnecki has argued that such claims have been based on crude population-wide analyses that have not taken account of changes in the composition of the community.
“The authors claiming a reduction in the incidence of melanoma in young Australians [have] failed to mention that the incidence was calculated for the entire population, and not the susceptible population,” he said.
Dr Czarnecki said that in the past 30 years the profile of the population has changed markedly, with a big upsurge in the proportion of people from Asia, the Pacific Islands, the Middle East and Sub-Saharan Africa – all regions where melanoma is much less common that in Australia.
He said the crude rate of melanoma in Australia was 526 per million in 2008, compared with two per million in Egypt, three per million in China and one per million in India.
“[There has been] a large number of dark skinned immigrants settling [in Australia],” Dr Czarnecki said. “These people have a low risk of developing melanoma, and if they are included in the total population when calculating incidence, [it] will appear lower than if immigration had not taken place. This apparent change in incidence might be used to support the impression that public health campaigns were working, even if they were not.”
Instead, in his study Dr Czarnecki calculated the incidence of melanoma excluding those who were born, or whose parents were born, in regions of low prevalence.
Using this method, he calculated that between 1982 and 2009 the incidence of melanoma in young people susceptible to the condition actually increased from 5.9 per 100,000 to 6.3 per 100,000. If young Maori and Aboriginal people were also excluded, the incidence per 100,000 rose from 6 to 6.8 over the same period.
‘The increase…occurred when many public health campaigns were run, and the age group studied was born and raised while these campaigns were in action,” Dr Czarnecki said. “Claims that [these] campaigns have been effective at reducing the incidence of melanoma in young Australians cannot be taken at face value.”
His warning came as study published in the journal Nature indicated that although high-rating SPF 50 sunscreens were effective in preventing sunburn and slowing the onset of skin cancer, they did not negate the cancer risk.
The study found that mice predisposed to developing melanoma took only about 30 per cent longer to develop the cancer when coated with SPF 50 sunscreen.