Increasing Incidence of Cutaneous Melanoma in Queensland, Australia

BACKGROUND: Queensland, Australia, had the world's highest incidence rates of invasive cutaneous melanoma in the 1970s. PURPOSE: The purpose of this study was to monitor trends in melanoma incidence in Queensland. METHODS: We studied two time periods in which ascertainment was comparable. RESULTS: In the 7.5 years up to 1987, the incidence of invasive melanoma in Queensland increased by more than one half in women (to 42.89 per 100,000) and more than doubled in men (to 55.81 per 100,000), with the most dramatic increase seen in men over age 50 years. This higher increase in men is a reversal of the previously higher rates in women. In Queensland, cumulative risks of total cutaneous melanoma (in persons aged 0-74 years), including preinvasive melanoma, have increased to one in 14 in men and to one in 17 in women. There were large increases in age-standardized incidence rates of thin lesions (less than 0.75 mm) in both sexes but not of in situ lesions, and there were also increases in thicker lesions, especially on the backs of males. CONCLUSIONS: Although increased awareness and earlier diagnosis appear to have accompanied increased incidence, increased exposure to solar UV radiation during the past 50 years appears to be the most likely explanation for the rise in incidence rates. IMPLICATIONS: A better understanding is needed of the causes of melanoma and of the complex relationships between constitutional factors, ambient UV radiation, and sun-exposure behavior.