Background: Australia has among the highest melanoma incidence rates globally. Understanding trends by tumour stage and anatomic site is critical for targeted prevention and early detection strategies. This study investigates long-term trends in invasive and in situ melanoma incidence across Australia by T stage, sex, and body site.
Methods: We used Australian population-based melanoma registry data from 1982 to 2016. Age-standardised incidence rates (ASRs) per 100,000 person-years were calculated using direct standardisation to the 2001 Australian Standard Population. We stratified analyses by sex, anatomic site, and tumour T category. Joinpoint regression was applied to quantify temporal trends in ASRs, estimating annual percent changes (APCs) and average annual percent changes (AAPCs).
Results: A total of 358,936 melanoma cases were included. The ASR of in situ melanoma increased steadily in both sexes, with higher rates in males. For invasive melanoma, T1 tumours showed a marked increase over time, while T4 tumours also rose in incidence, albeit at lower absolute rates. Trends varied by body site: trunk melanomas were most common in males, whereas lower limb melanomas predominated in females. Joinpoint analysis identified multiple inflection points, with the greatest AAPC observed in T1 lesions among males.
Conclusions: Despite public health efforts, both early-stage and late-stage melanoma incidence rates continue to rise in Australia. The simultaneous increase in T1 and T4 melanomas suggests that while early detection has improved, there remains a cohort presenting with advanced disease. These findings highlight the need for renewed public health messaging and targeted screening strategies, particularly for high-risk populations.