Ghassan Guorgis, Chris D. Anderson, Johan Lyth, Magnus Falk
DOI: 10.2340/00015555-3486

Actinic keratosis is the most common actinic lesion in fair-skinned populations. It is accepted as an indicator of actinic skin damage and as an occasional precursor of squamous cell carcinoma. The aim of this study was to investigate, in a cohort of patients with a diagnosis of actinic keratosis, the relative risk of developing skin cancer during a follow-up period of 10 years. This registry-based cohort study compared a cohort of 2,893 individuals in south-eastern Sweden, who were diagnosed with actinic keratosis during the period 2000 to 2004, with a matched-control cohort of 14,668 individuals without actinic keratosis during the same inclusion period. The subjects were followed for 10 years to identify skin cancer development in both cohorts. Hazard ratios with 95% confidence intervals (95% CI) were used as risk measures. Individuals in the actinic keratosis cohort had a markedly higher risk for all skin cancer forms compared with the control cohort (hazard ratio (HR) 5.1, 95% CI 4.7–5.6). The relative risk was highest for developing squamous cell carcinoma (SCC) (HR 7.7, 95% CI 6.7–8.8) and somewhat lower for basal cell carcinoma (BCC) (HR 4.4, 95% CI 4.1–5.0) and malignant melanoma (MM) (HR 2.7 (2.1–3.6). Patients with a diagnosis of actinic keratosis were found to be at increased risk of developing SCC, BCC and MM in the 10 years following diagnosis of actinic keratosis. In conclusion, a diagnosis of actinic keratosis, even in the absence of documentation of other features of chronic sun exposure, is a marker of increased risk of skin cancer, which should be addressed with individually directed preventive advice.

Actinic keratosis is a common skin lesion associated with chronic exposure to sun. In most cases actinic keratosis is harmless, but it occasionally transforms into squamous cell carcinoma. This study included 2,893 patients with actinic keratosis, and investigated their 10-year risk of developing skin cancer, compared with a control group of 14,668 patients without actinic keratosis. Patients with actinic keratosis were found to have a more than 5 times increased risk of getting skin cancer. With regard to specific types of skin cancer, this increased risk in patients with actinic keratosis was highest (greater than 7 times higher) for squamous cell carcinoma, greater than 4 times higher for basal cell carcinoma, and almost 3 times higher for malignant melanoma. In conclusion, actinic keratosis is an important indicator of increased risk of skin cancer.