Danish Registry Study Shows Rising cSCC and CIS Incidence Over 18 Years
Key Takeaways
Nationwide Danish registry data show continued increases in cutaneous squamous cell carcinoma (cSCC) and cSCC in situ (CIS) incidence from 2005 to 2023, while keratoacanthoma (KA) declined.
There were significant sex- and site-specific differences, with male predominance on the head and neck and higher lower-limb incidence among female individuals.
Trends appeared stable for individuals younger than 50 years, which authors said may reflect early effects of prevention efforts.
Incidence rates of cutaneous squamous cell carcinoma (cSCC) and cSCC in situ (CIS) have continued to rise in Denmark over nearly two decades, while keratoacanthoma (KA) incidence has declined, according to a large population-based registry study.
Investigators using data from the Danish Pathology Registry and Danish Cancer Registry identified 109,787 histologically confirmed first-time diagnoses of cSCC, CIS, or KA among more than 95,000 (n = 95,352) individuals aged 20 years or older between 2005 and 2023. The cohort was evenly distributed by sex (50.9% male; 49.1% female). Analyses assessed age-standardized incidence rates (ASIRs), age-specific rates, and estimated annual percentage changes (EAPCs), stratified by sex, age, and anatomic site.
According to the data, ASIRs for cSCC increased steadily in both sexes, with EAPCs of 2.6% in male individuals and 3.1% in female individuals, reaching 131.6 and 77.7 per 100,000 person-years, respectively, by 2023. CIS data showed a significant rise (EAPCs of 6.4% in males and 5.8% in females). KA incidence declined over the study period. Face, scalp, and neck were the predominant sites for cSCC and CIS, especially in males. Female individuals demonstrated higher ASIRs on the lower limbs across all three keratinocyte neoplasms. KA most commonly affected the extremities overall.
Age-stratified analyses showed higher incidence rates among female individuals aged 40 to 59 years compared with male individuals across all neoplasm types, while trends for cSCC and KA were stable among individuals younger than 50 years.
"In this nationwide cohort study presenting the most comprehensive dataset of incident cSCC, CIS, and KA, with 109 787 histologically confirmed patient cases, covering nearly 2 decades and spanning across all Danish health care sectors, incidence of cSCC and CIS continued to rise, consequently affecting more people, and sex differences diminished," the authors concluded. "Stabilizing trends in individuals younger than 50 years may indicate early prevention effects. Findings of this study have the potential to influence future surveillance activities and clinical care through attention to sex, age, and anatomical site. “Stabilizing trends in individuals younger than 50 years may indicate early prevention effects.”
Source: Duffau K, et al. JAMA Dermatology. 2026. doi:10.1001/jamadermatol.2025.5700