The incidence and multiplicity rates of keratinocyte cancers in Australia.

ABSTRACT

OBJECTIVES: To assess the incidence and multiplicity of keratinocyte cancers (basal cell carcinoma [BCC] and squamous cell carcinoma [SCC]) excised in Australia, and to examine variations by age, sex, state, and prior skin cancer history. DESIGN: Analysis of individual-level Medicare data for keratinocyte cancer treatments (identified by eight specific MBS item codes) during 2011-2014. Histological data from the QSkin prospective cohort study were analysed to estimate BCC and SCC incidence. SETTING: A 10% systematic random sample of all people registered with Medicare during 1997-2014. PARTICIPANTS: People aged at least 20 years in 2011 who made at least one claim for any MBS medical service during 2011-2014 (1 704 193 individuals). MAIN OUTCOME MEASURES: Age-standardised incidence rates (ASRs) and standardised incidence ratios (SIRs). RESULTS: The person-based incidence of keratinocyte cancer excisions in Australia was 1531 per 100 000 person-years; incidence increased with age, and was higher for men than women (SIR, 1.43; 95% CI, 1.42-1.45). Lesion-based incidence was 3154 per 100 000 person-years. The estimated ASRs for BCC and SCC were 770 per 100 000 and 270 per 100 000 person-years respectively. During 2011-2014, 3.9% of Australians had one keratinocyte cancer excised, 2.7% had more than one excised; 74% of skin cancers were excised from patients who had two or more lesions removed. Multiplicity was strongly correlated with age; most male patients over 70 were treated for multiple lesions. Keratinocyte cancer incidence was eight times as high among people with a prior history of excisions as among those without. CONCLUSIONS: The incidence and multiplicity of keratinocyte cancer in Australia are very high, causing a large disease burden that has not previously been quantified.