Incidence of Cutaneous Squamous Cell Carcinoma and Carcinoma in Situ Continues to Rise

Key Clinical Takeaways: 

• Design/Population: This nationwide, population-based, real-world study analyzed first-time, histologically confirmed diagnoses of cutaneous squamous cell carcinoma, carcinoma in situ, and keratoacanthoma among adults over a nearly 20-year period.
• Key Outcomes: Incidence of cutaneous squamous cell carcinoma and carcinoma in situ increased steadily over time, while keratoacanthoma incidence declined. Distinct patterns were observed by sex, age, and anatomical site.
• Clinical Relevance: These findings highlight the growing burden of keratinocyte neoplasms and underscore the importance of continued surveillance, prevention strategies, and awareness of demographic and anatomic risk patterns in clinical practice.

Results from a real-world study have demonstrated that the incidence of cutaneous squamous cell carcinoma and cutaneous squamous cell carcinoma in situ has steadily increased over the past 2 decades, emphasizing the need for monitoring strategies and targeted person-centered care.

“Cutaneous squamous cell carcinoma, [cutaneous squamous cell carcinoma] in situ, and keratoacanthoma pose growing public health challenges, due to their associated morbidity, health care burden and costs,” stated Kristine Duffau, MD, Danish Cancer Institute, Copenhagen, Denmark, and coauthors. “However, many countries lack systematic registration of these extremely frequent keratinocyte neoplasms.” 

In this population-based study, researchers used the Danish Pathology Registry and Cancer Registry to collect data from 95,352 patients 20 years of age or older who received a first-time diagnosis of cutaneous squamous cell carcinoma (n = 54,563), cutaneous squamous cell carcinoma in situ (n = 31,712), or keratoacanthoma (n = 23,512) between January 2005 and December 2023. Patients were stratified based on sex (male n = 55,891; female n = 53,896), age, and anatomical site and data was used to generate age-standardized incidence rates (ASIRs) and age-specific incidence rates per 100,000 persons/years with corresponding estimated annual percentage changes (EAPCs). 

At analysis, the incidence of cutaneous squamous cell carcinoma increased by 2.6% in male patients and 3.1% in female patients, reaching 131.6 per 100,000 person-years and 77.7 per 100,000 person-years, respectively. The incidence of cutaneous squamous cell carcinoma in situ increased by 6.4% in male patients and 5.8% in female patients. The incidence of keratoacanthoma declined. 

Stratified analyses revealed that male patients with cutaneous squamous cell carcinoma and cutaneous squamous cell carcinoma in situ more commonly exhibited predilection sites on the face, scalp, and neck, whereas female patients more frequently exhibited predilection sites on the lower limbs. Female patients aged 40 to 59 years had higher incidence rates of keratinocyte neoplasms compared with male patients in the same age group. Incidence trends for cutaneous squamous cell carcinoma and keratoacanthoma were stable among patients younger than 50 years, potentially indicating positive effects of early prevention efforts. 

According to Dr Duffau et al, “findings of this study have the potential to influence future surveillance activities and clinical care through attention to sex, age, and anatomical site.”

Source: 

Duffau K, Baandrup L, Frederiksen K, et al. Incidence trends of cutaneous squamous cell carcinoma, carcinoma in situ, and keratoacanthoma by sex, age, and anatomical site. JAMA Dermatol. Published online: January 28, 2026. doi: 10.1001/jamadermatol.2025.5700