Phenol peels as a novel therapeutic approach for actinic keratosis and Bowen disease: Prospective pilot trial with assessment of clinical, histologic, and immunohistochemical correlations

Background Although chemical peels may be used for precancerous lesions, no histologic or immunohistochemical studies have been performed to validate clinical impressions and/or outcome. Objective Our purpose was to investigate the efficacy and prognostic relevance of phenol peels in Japanese patients with actinic keratosis and Bowen disease using clinical and histologic criteria. Methods A total of 46 patients were treated with phenol peels, and followed up for at least 1 year after treatment. Biopsy specimens were taken before and after treatment. Cases of complete response were classified by the number of treatment sessions. We evaluated parameters for epidermal thickness, proliferation, dysplasia, and apoptosis, and clinical characteristics to correlate phenol peels with assessments of efficacy, patient-selection criteria, and risk for transformation to cutaneous squamous cell carcinoma. Results There were 39 (84.8%) patients with a complete response after one to 8 treatment sessions. Statistically, differences in clinical improvement with peels and the number of treatment sessions correlated with histology, personal history of skin cancer, tumor thickness, and cyclin A expression. Limitations This study was a prospective pilot trial. Blinded, placebo-controlled, randomized studies would be ideal. Conclusion We conclude that phenol peels are very effective for treating precancerous lesions of actinic keratosis and Bowen disease. In addition, our study clearly demonstrates that tumor thickness and cyclin A could be specific and useful markers as adjunctive diagnostic tools to predict the efficacy of phenol treatment of these lesions.