Keratinocyte Cancers

Keratinocyte cancers (KC) include basal and squamous cell carcinomas that arise from keratinocytes or their precursors. KCs are the most common malignancies in humans. Basal cell carcinoma (BCC) has higher incidence rates, but squamous cell carcinoma (SCC) causes most deaths. Despite increasing incidence rates, the mortality rates have not changed markedly in recent years. The geographic and demographic features of these tumors have remained consistent over the past several decades, with a gradient of increasing incidence rates with proximity to the equator, predominantly affecting fair-skinned populations. Risk increases with age, is higher in men than women, and is associated with artificial as well as natural exposure to UV light. There is emerging evidence that these malignancies, particularly BCCs, may be increasing in younger adults and among women. While basal and squamous cell carcinomas share etiological factors, the relative importance of these factors, pattern of exposure, molecular alterations, and even the factors themselves differ.