Background: Actinic keratoses (AKs) are precancerous epidermal lesions found most frequently on areas of the skin exposed to the sun. Several case studies published recently have indicated that 5% imiquimod cream, currently licensed for the treatment of genital warts, may be an effective treatment for AK.
Objective: To assess the efficacy and safety of imiquimod for the treatment of AK.
Design: Patients in this randomized, double-blind, vehicle-controlled study applied 5% imiquimod cream or vehicle to AK lesions 3 times per week for a maximum of 12 weeks or until lesions had resolved. In the event of an adverse reaction, application of imiquimod was reduced to 1 or 2 times per week. Rest periods were also allowed if necessary.
Setting: A specialized outpatient dermatology clinic within a state-funded hospital in Germany.
Patients: The study population was aged 45 to 85 years. Of 52 patients screened, 36 men and women with AK confirmed by histological diagnosis were enrolled. Patients were excluded from the study if they did not have a histological diagnosis for AK, if they were older than 85 years, or if they did not comply with the protocol. All patients had responded to a notice asking for volunteers.
Main outcome measures: The number and appearance of lesions were evaluated before, during, and after treatment. All adverse effects were recorded.
Results: Lesions treated with 5% imiquimod cream were clinically cleared in 21 (84%) of 25 patients and partially cleared in 2 (8%). Clearance was histologically confirmed 2 weeks after the last application of imiquimod in all patients clinically diagnosed as lesion free. Only 10% of patients treated with imiquimod were clinically diagnosed with recurrence 1 year after treatment. No reduction in the size or number of AK lesions was observed in vehicle-treated patients. Adverse effects reported by patients treated with imiquimod included erythema, edema, induration, vesicles, erosion, ulceration, excoriation, and scabbing. However, imiquimod was well tolerated since all patients completed the 12-week treatment. Only a few, mild adverse reactions to the vehicle cream were reported.
Conclusion: Application of 5% imiquimod cream for 12 weeks is an effective and well-tolerated treatment for AK.