Prevalence, incidence and trends of keratinocyte carcinoma in Denmark 2007-2021: A population-based register study.

Introduction: The incidence of keratinocyte carcinoma (KC), i.e., basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), is increasing worldwide, placing a significant burden on healthcare resources. This is especially the case for tumors requiring surgical intervention. It remains unclear whether this increase is a result of the population aging or a genuine increase in risk of skin cancer. Understanding age-adjusted incidence trends of KC is crucial for improving future management of the disease. We studied these trends in a large nationwide cohort, focusing on large, invasive, and surgically challenging tumors.

Methods: Information on all incident cases of BCC and SCC in Denmark was extracted from population-based databases in the calendar years 2007-2021. Age-adjusted incidence rates were calculated, standardized to the 2013 European Standard Population. Average annual percentage changes were estimated using Joinpoint regression models. Incidence trends for larger, more invasive tumors (tumor (T) category of ≥T2), and of those in the head and neck area, were elucidated with descriptive statistics.

Results: We found 183,338 patients with a first-time incidence of BCC and 42,233 patients with a first-time incidence of SCC in the period 2007-2021. The incidence rate, adjusted for age, increased from 252 to 338 per 100,000 for BCC and from 49 to 104 per 100,000 for SCC. For SCC, the increase was particularly pronounced in the last two years of the study period. Tumors ≥T2, and those in the head and neck area, increased markedly.

Conclusion: KC is the most common type of cancer worldwide, and the age-adjusted incidence rates of BCC and SCC increased significantly from 2007 to 2021, as did tumors with a higher T category and those located in anatomically sensitive areas. Since the primary treatment for many of these tumors is surgical, this raises concern about the strain on future healthcare resources.