EDINBURGH – Contrary to the perception that most melanoma deaths result from thick melanomas, long-term data from Australia show that more people die who initially present with thin melanomas.
Among 4,218 Australians who died from melanoma between 1990 and 2009, thin melanomas (1 mm or less) accounted for 19% of melanoma deaths overall, but increased steadily from 14% of deaths in 1990-1994 to 23% in 2005-2009.
During the most recent time period (2005-2009), more people died from thin melanomas (296 deaths, 23%) than from thick melanomas more than 4 mm in thickness (186 deaths, 14%) or from metastatic presentations (207 deaths, 16%).
The number of deaths in the intermediate thickness categories was also higher for lesions of thickness 1.01-2.0 mm (272 deaths, 21%) than for lesions of thickness 2.01-4.0 mm (267 deaths, 20%).
The patterns of mortality were essentially unchanged when the analyses were restricted to patients with only one primary melanoma, Dr. David Whiteman and Dr. Catherine Olsen of the QIMR Berghofer Medical Research Institute, Brisbane, Australia, reported at the 15th World Congress on Cancers of the Skin.
The melanoma incidence has been rising steadily around the world, mostly because of the greater numbers of thin lesions being diagnosed. The perception that most people who die from melanoma present initially with thick lesions is widespread, but the veracity of this proposition has never been tested because population-based data describing total mortality by the thickness of the primary tumor are scarce, according to the researchers. They used linked histology and death data from the Queensland Cancer Registry, where notification of melanoma has been compulsory since 1982, to calculate age-standardized mortality rates for each year for all melanomas, and by thickness of the first primary lesion. Overall, 67% of patients were male, 68% presented with a single primary lesion, and 68% of all melanomas were thin (1 mm or less).
Deaths from melanoma were most common among those who were in the seventh and eighth decades of life, male, or had a melanoma arising on the trunk. As expected, the intervals from diagnosis to death were significantly shorter for thicker tumors than thinner tumors, Dr. Whiteman and Dr. Olsen noted in the poster presentation.
The average annual rate of change in melanoma mortality increased significantly for men for thin lesions and those of intermediate thickness. Mortality rates from metastatic lesions, however, declined during the observation period.
“From a public health perspective, it can be argued that primary prevention activities aimed at reducing the occurrence of melanoma in the entire population should be accorded the highest priority,” the authors concluded at the meeting, sponsored by the Skin Cancer Foundation.