by ecancer reporter Janet Fricker

Thin melanomas (defined as lesions less than 1mm thick), led to more patient deaths than thick melanomas (defined as lesions thicker than 4mm) in a study published in the Journal of Investigative Dermatology.

The Australian study showed that the proportion of deaths attributable to thin melanomas in Queensland to be on the rise.

While patients with thin melanomas have only a minimally increased risk of dying compared to the general population, patients with thicker melanomas have a much higher risk of mortality.

Such data has led to the perception that most deaths from melanomas are due to thick lesions.

However, data describing population distribution of lethal melanomas according to thickness has seldom been reported.

In the current study David Whiteman and colleagues, from QIMR Berghofer Medical Research Institute, Brisbane, analysed data from the Queensland Cancer Registry for 4,218 patients who between 1990 and 2009 died from melanoma.

The data included information on sex, age group, month and year of death, thickness, histology and anatomic site.

Results showed that thin melanomas accounted for 68% of all melanomas and overall 19% of melanoma deaths but that the number of deaths attributable to thin melanomas increased from 14% between 1990 and 1994 to 23% between 2005 and 2009.

In contrast there was only a slight rise in the proportion of deaths from thick lesions; from 11% between 1990 and 1994 to 14% between 2005 and 2009.

“These data demonstrate that thin melanomas comprise a substantial fraction of the overall burden of lethal melanomas in the high incidence population of Queensland,” write the authors.

The higher reported incidence of thin melanomas, they suggest, may be due to increased early detection, but not all melanomas that have been diagnosed will go on to cause symptoms or death.

“While early detection strategies should continue, clinicians must be mindful that thin melanomas contribute substantially to overall melanoma mortality, not withstanding their overall favourable prognosis,” write the authors, adding that identifying the clinical and molecular features of thin melanomas that confer poor prognosis should be the focus of continued research.

Reference

D Whiteman, P Baadez, C Olsen, et al. More people die from thin melanomas (<1mm) than thick melanomas (>4mm) in Queensland, Australia. Journal of Investigative Dermatology.