eratinocyte carcinoma comprises basal and squamous cell carcinomas, and is the most common malignant dis ease in Canada and the United States. [1][2][3][4][5] Although kera tinocyte carcinoma has a low mortality rate, it is associated with substantial morbidity and impaired quality of life. 2,6,7 Among can cers, it also ranks fifth in health care costs in the US. 8 Epidemiological studies of keratinocyte carcinoma in North America are limited by its exclusion from most cancer regis tries. 9 Previous studies found that higher overall incidence of keratinocyte carcinoma is associated with male sex, 10-14 older age [15][16][17] and higher socioeconomic status. [18][19][20][21] However, differ ences in the incidence and mortality rates of keratinocyte car cinoma by sex in relation to age and socioeconomic status have not been well characterized.A better understanding of the epidemiology of keratinocyte carcinoma in Canada and differences by sex would inform public health initiatives, health services policy and patient education strategies. This is particularly relevant now, given the recent regu latory approval of systemic immunotherapies for locally advanced or metastatic squamous and basal cell carcinoma. [22][23][24][25] Our objective was to identify the populationbased incidence and mortality trends of keratinocyte carcinoma in Ontario, Canada over 2 decades and to evaluate sex differences.
MethodsWe conducted a populationbased, retrospective observa tional study of health administrative data sets that were linked using unique encoded identifiers and analyzed at ICES. We reported the study according to the Reporting of Studies Con ducted Using Observational RoutinelyCollected Health Data (RECORD) checklist. 26 Research Incidence and mortality rates of keratinocyte carcinoma from 1998-2017: a population-based study of sex differences in Ontario, Canada