Objective: To examine evidence about the natural history and management of actinic keratoses (AKs).
Search Strategy: We searched the MEDLINE database from January 1966 to January 2001, the Cochrane Controlled Trials Registry, and a bibliographic database of articles about skin cancer. We identified additional articles from reference lists and experts.
Selection Criteria: We selected 45 articles that contained original data relevant to treatment of actinic keratoses, progression of AKs to squamous cell cancer (SCC ), means of identifying a high-risk group, or surveillance of patients with AKs to detect and treat SCCs early in their course.
Data Collection and Analysis: We abstracted information from these studies to construct evidence tables. We also developed a simple mathematical model to examine whether estimates of the rate of progression of AK to SCC were consistent among studies. Finally, we analyzed data from the Medicare Statistical System to estimate the frequency of procedures attributable to AK among elderly beneficiaries.
Main Results: The yearly rate of progression of an AK in an average-risk person in Australia is between 8 and 24 per 10,000. High-risk individuals with multiple AKs have progression rates as high as 12–30 percent over 3 years. Indirect evidence suggests that 2 percent of squamous cell cancers originating in AKs metastasize, and 7 percent recur locally. Over the course of a year, from 20–25 percent of AKs regress.
There are no studies comparing the long-term efficacy or morbidity of topical treatment versus surgical treatment for AKs.
Conclusions: Available data are insufficient to determine whether immediate treatment of all AKs, or a strategy of selective treatment for AKs that develop suspicious characteristics, result in different outcomes. An important information gap is how often squamous cell cancer metastasizes early in its course. The highest priorities for future research are controlled trials of different strategies for the long-term management of patients who have actinic keratoses; particularly multiple lesions; registry studies to assess morbidity and mortality related to squamous cell cancer in the elderly; and patient-centered research on patients’ preferences for, and quality of life related to, different treatments.