Friday 8 August 2008
Thick melanomas: the problem continues
The incidence of the most dangerous kind of skin cancer, thick melanoma, is still not decreasing in New Zealand nearly
15 years after early detection strategies were introduced to educate the public.
Researchers from the University of Otago analysed figures from the NZ Health Information Service of registered cancers
to see if thick melanomas (greater than 3mm) had decreased in incidence between 1994 and 2004 because of detection
strategies. The study has just been published in the New Zealand Medical Journal (August8)
“Regrettably the answer is that we didn’t find any decrease of thick melanoma over the last decade,” says Dr 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. Overall though, Maori have a
significantly lower rate of melanoma compared to non-Maori.
The researchers believe there are two possible reasons for the lack of progress in combating this difficult disease
which in 2004 resulted in 249 deaths. They say 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. These strategies include brochures and pamphlets describing melanomas with advice on what to do.
Dr Reeder believes that the situation needs to be monitored and that this study is an important baseline to work from in
that regard. The university of Otago researchers also support a re-examinaton of the early detection strategies to see
if early recognition of more dangerous thick melanomas can be improved.
“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.”
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.
The NZ Health Information Service provided the melanoma registration data from the NZ Cancer Registry and the extraction
of the data was funded by the Cancer Society of New Zealand. Assoc Prof Cox and Dr Sneyd receive support from the
University of Otago Director’s Cancer Research Trust. Dr Reeder and the Cancer Society Social & Behavioural Research Unit receive support from the Cancer Society of New Zealand and the University of Otago.
For images of thick melanoma go to www.dermet.org.nz and click on melanoma
ends