ABSTRACT
Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, Texas, U.S.A.
INTRODUCTION
The incidence of skin cancer is rapidly rising with an occurrence of 1.2 million new
cases each year in the United States alone (1) and 1% to 2% of the Australian popu-
lation being affected by nonmelanoma skin cancer (NMSC) annually (2). NMSCs,
including squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), are the
most frequently diagnosed neoplasm. Epidemiological evidence of chronic over-
exposure in sun-exposed areas of the body shows that people with outdoor occu-
pations have a higher incidence of SCC than do people who work indoors (3).
Additionally, the face, head, neck, back of the hands, and arms are predominant
sites for development of NMSCs. It is becoming increasingly clear that solar ultra-
violet (UV) radiation is a major causative factor in the development of NMSC and
was the first identified human carcinogen. Sun exposure is currently the leading
environmental risk factor for the development of NMSC in humans (4,5). There
are several reviews that discuss evidence showing that solar radiation is strongly
implicated in the induction of human skin cancer (6-9).
