title: Epidemiology of actinic keratoses and squamous cell carcinoma.
abstract: OBJECTIVE
  The purpose of this article was to review the frequency, distribution, and determinants of actinic keratoses (AKs) and squamous cell carcinoma (SCC).
  
  
  METHODS
  A review of the literature was done.
  
  
  RESULTS
  AKs are extremely common lesions on the sun-exposed skin of Caucasian persons. The most important risk factors are a combination of genetic propensity ("fair skin phenotype") and cumulative sun exposure. Their prevalence increases with advancing age. The epidemiology of SCC is virtually the same, but the lesions occur most often on the head rather than on the upper extremities where most AKs are located. AKs are the most important risk factor identifying those most predisposed to the development of an SCC.
  
  
  CONCLUSIONS
  AKs are a reliable marker for those people most predisposed to development of an invasive SCC. In addition, AKs are probably an early stage in a biologic continuum that culminates in SCC. However, there are many more AKs than SCCs, and it is difficult to predict exactly which lesions will progress to invasive cancer.
authors.affiliation: Arizona Cancer Center, Tucson, Arizona and the University of Arizona Health Sciences Center, Tucson, Arizona, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Salasche
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000453:epidemiology*; D006801:Humans; D007642:Keratosis / Q000453:epidemiology*; D010787:Photosensitivity Disorders / Q000453:epidemiology*; D012878:Skin Neoplasms / Q000453:epidemiology*