Temporal trends in the incidence rates of keratinocyte carcinomas from 1978 to 2018 in Tasmania, Australia: a population-based study

Objectives We described incidence trends of keratinocyte carcinomas (KCs)—namely basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)—in the Australian state of Tasmania. Methods We identified histologically confirmed KCs within the Tasmanian Cancer Registry (TCR) and conducted assessments to ensure data quality. Age-standardised incidence rates were calculated for first (1985–2018) and annual KCs (1978–2018). Average annual percentage changes were computed using Joinpoint regression models. Results The TCR is a reliable source of KC data. A total of 83,536 people were registered with a KC between 1978 and 2018. Age-standardised incidence rates of first KCs increased on average by 3% per annum for BCCs and 4% per annum for SCCs, reaching 363/100,000 and 249/100,000 in 2018, respectively. Age-standardised incidence rates of annual KCs increased on average by 5% per annum for BCCs and 6% per annum for SCCs, up to 891/100,000 and 514/100,000 in 2018, respectively. This increase was steeper for females than males and highest during the late 1980s and early 1990s. A change in trend around 2014 suggested that incidence rates have started to decline. Conclusion While the incidence of KCs in Tasmania increased substantially over 41 years, rates have recently plateaued and started to decline. The findings may reflect changes in sun exposure behaviours due to awareness campaigns, but high incidence rates in 2018 indicate that KCs still pose a substantial burden to this population.