Are all melanomas dangerous?

The increased incidence of cutaneous malignant melanoma, together with only minor changes in mortality, has brought into question the existence of a melanoma epidemic. The discrepancy between incidence and mortality suggests that most newly diagnosed melanomas have indolent behaviour. This review summarizes the most recent epidemiological findings regarding the incidence of cutaneous malignant melanoma, mortality, Breslow thickness and clinical stage. Studies published between 2005 and 2010 with more than 2,000 test subjects were included in this review. These studies all report an increase in incidence of melanoma during the last few decades, with by far the highest increase in tumours at a very early stage (T1 or IA). Little or no change was seen in mortality. However, increases in both mortality and incidence of thick melanomas were found in the oldest subgroups, especially in men. These findings indicate the existence of a certain degree of overdiagnosis of melanoma. They also indicate the existence of two different types of epidemic, for younger and older subgroups.