Actinic keratosis: update on field therapy.

Actinic keratosis is widely considered a field disease that is rarely limited to a single clinically apparent lesion. Field-directed therapies, such as ingenol mebutate, imiquimod, and photodynamic therapy, aim to treat not only clinically visible lesions, but also subclinical disease that is thought to exist along the same continuum as actinic keratosis and squamous cell carcinoma. These field treatments have shown efficacy compared to placebo as well as in long-term follow-up studies when compared to lesion-directed cryotherapy alone. Field therapy in combination with lesion-directed treatment will allow the practitioner to further optimize efficacy as well as patient preference and convenience. As the incidence of nonmelanoma skin cancer continues to rise, these treatment modalities provide new options to halt the progression of actinic keratosis, and thereby reduce the incidence of nonmelanoma skin cancer and its burden on our healthcare system.