RESUMO
BACKGROUND: Actinic keratoses are the most common actinic lesions on Caucasian skin. Cryosurgery with liquid nitrogen is commonly used to treat actinic keratoses, but there have been few studies examining the true rate of cure in everyday dermatologic practice. AIM: To determine prospectively the true efficacy of cryosurgery as a treatment for actinic keratoses in everyday dermatologic practice. METHODS: A prospective, multicentered study (a subsidiary study of a photodynamic therapy trial) was performed. Patients with untreated actinic keratoses greater than 5 mm in diameter on the face and scalp were recruited. Eligible lesions received a single freeze-thaw cycle with liquid nitrogen given via a spray device and were reviewed 3 months thereafter. Each center used their preferred freeze time. The only treatment criterion was complete freezing of actinic keratoses and a 1-mm rim of normal skin. Treated lesions were assessed as complete response or noncomplete response. The influence of the duration of freeze, cosmetic outcomes, and adverse events were examined. RESULTS: Ninety adult patients from the community with 421 eligible actinic keratoses were recruited. The overall individual complete response rate was 67.2%[SEM = +/-3.5%; 95% confidence interval (CI) = 60.4-74.1%]. Complete response was 39% for freeze times of less than 5 s, 69% for freeze times greater than 5 s, and 83% for freeze times greater than 20 s. Cosmetic outcomes were good to excellent in 94% of complete response lesions. The main adverse events were pain, stinging, and burning during treatment, and hypopigmentation after healing. CONCLUSIONS: Cryosurgery is an effective treatment for actinic keratoses. The true complete response rate is significantly lower than that previously reported. The freeze duration influences successful treatment. Adverse events are mild and well tolerated.