The concept of field cancerization (FC) was first used to describe the presence of islands of pathologic tissue in the normal tissue of patients with oropharyngeal carcinomas. Cutaneous FC describes the presence of widespread epidermal atypia, including multiple actinic keratoses (AK), keratinocyte carcinomas (squamous cell carcinomas in situ [SCCis], and invasive squamous cell cancers [SCCs]) arising in chronically sun-damaged skin (the "field").

Ultraviolet radiation (UVR) is the greatest risk factor for FC of the skin. UVR causes FC by inducing key genetic mutations that alter appropriate epidermal cell recycling and apoptotic regulators. Mutations in these markers, especially TP53 and NOTCH, allow for the progression from AK to invasive cutaneous cancers (eg, SCC).

Present data, although limited, suggests both a steady increase in AK prevalence and keratinocyte carcinoma incidence in the United States. At-risk populations include persons of increasing age, chronic UVR exposure, light skin, male sex, and immunosuppression (eg, solid organ transplant recipients, patients with chronic lymphocytic leukemia).