Basal cell carcinoma: an emerging epidemic in women in Iceland

BACKGROUND: An epidemic of basal cell carcinoma (BCC) has led to a significant healthcare burden in white populations. OBJECTIVES: To provide an update on incidence rates and tumour burden in an unselected, geographically isolated population that is exposed to a low level of ultraviolet radiation. METHODS: This was a whole-population study using a cancer registry containing records of all cases of BCC in 1981-2017. We assessed BCC incidence according to age, residence and multiplicity and assessed trends using join-point analysis. Age-standardized and age-specific incidence rates were calculated along with cumulative and lifetime risks. RESULTS: During the study period, the age-standardized incidence rates increased from 25.7 to 59.9 for men, and from 22.2 to 83.1 for women (per 100 000). Compared with the single-tumour burden, the total tumour burden in the population was 1.72 times higher when accounting for multiplicity. At the beginning of the study period, the world-standardized rates in men and women were similar, but by the end of the study period the rates were 39% higher in women (83.1 per 100 000, 95% confidence interval 77.9-88.3) than in men (59.9 per 100 000, 95% confidence interval 55.6-64.2). This increase was most prominent in women on sites that are normally not exposed to ultraviolet radiation in Iceland: the trunk and legs. CONCLUSIONS: This is the only reported population in which the incidence of BCC is significantly higher in women than in men. The period of notable increase in BCC lesions correlates with the period of an increase in tanning beds and travel popularity. The high multiplicity rates suggest that the total tumour burden worldwide might be higher than previously thought.