Skin cancer incidence still unabated

The incidence of melanoma, the most dangerous kind of skin cancer, remains unabated, in spite of early detection strategies introduced 15 years ago.

University of Otago researchers analysed figures from the New Zealand cancer registry to see whether thick melanomas (three mm thickness) had decreased between 1994 and 2004 because of detection strategies.

"Regrettably the answer is that we didn't find any decrease of thick melanoma over the last decade," said Tony Reeder. "There was the possibility that early detection and greater public awareness may have had an impact on later development of thick melanoma, but so far that is not the case."

Of those diagnosed with melanoma the proportion with thick melanoma is greater for older people, for males compared to females and for Maori compared to non-Maori and for those diagnosed with nodular melanoma.

Researchers believe there are two possible reasons for the lack of progress in combating this difficult disease which caused 249 deaths in 2004.

They said it may be too early to see any impact on thick melanomas of early detection, or the strategies may not be working as well as expected as they are not allowing the identification of some melanomas early enough.

Reeder believed that the situation needs to be monitored and that this study is an important baseline to work from in that regard. "The problem is that it is often quite difficult to identify thick melanomas early on."

"They tend to have a nodular shape, but don't necessarily stick out above the surrounding skin or have an irregular edge. They're not always dark either, and can be quite pale and flat," he added.

Similar issues are now surfacing internationally where despite widespread information about early detection of thick melanoma, many are being missed and the incidence rate has not declined as expected.