9 Shade Planning for America’s Schools Chapter 1 Basal Cell Cancer Typically occurring on the most sun-damaged parts of the body, basal cell carcinoma is a slow-growing cancer that begins as a raised lump on the skin and eventually breaks open to form an exposed sore. Although most of these types of cancers are colorless, some are dark in color. Like other skin cancers, basal cell cancer usually appears in middle age, as a result of UV radiation exposure during childhood or adolescence. Squamous Cell Cancer Squamous cell cancer is a more aggressive form of skin cancer that ultimately resembles basal cell cancer in appearance. It often follows a pre-cancerous condition called actinic keratosis, which is a dry and crusty area on the skin. Both basal cell and squamous cell carcinoma usually result from chronic exposure to UV radiation over a period of years. Melanoma By far, the most serious consequence of exposure to UV radiation is malignant melanoma. Unlike the other two types of skin cancer, basal cell and squamous cell, melanomas involve the dark pigmented cells of the skin, the melanocytes. A growing body of evidence indicates that intermittent sun exposure, as opposed to chronic sun exposure, causes this most deadly of skin cancers. Of particular concern, findings from certain studies point to childhood exposure to sunlight, especially severe childhood sunburn, as an indicator for melanoma as an adult. 12, 13, 14, 15 12 Westerdahl J, Olsson H, Ingvar C. At what age do sunburn episodes play a crucial role for the development of malignant melanoma. Eur J Cancer 1994; 30A(11):1647-54. 13 Zanetti R, Franceschi S, Rosso S, Colonna S, Bidoli, E. Cutaneous melanoma and sunburns in childhood in a southern European population. Eur J Cancer 1992;28A(6-7):1172-76. 14 Elwood JM, Whitehead SM, Davison J, Stewart M, Galt M. Malignant melanoma in England: risks associated with naevi, freckles, social class, hair colour, and sunburn. Int J Epidemiol 1990;19(4):801-10. 15 Gandini S, Sera F, Cattaruzza MS, et al. Meta-analysis of risk factors for cutaneous melanoma: II. Sun exposure. Eur J Cancer 2005;41:45-60. Sun Protection Is the Key The vast bulk of skin cancers in the U.S. are due to excessive skin exposure to UV radiation from the sun, so sun protection is the key to preventing the disease. Martin Weinstock, MD, PhD Director of Dermatoepidemiology at Brown University and Chair of the American Cancer Society (ACS) Skin Cancer Advisory Board Where Can I Find More Information? Chapter 5, “The Earth-Sun Relationship,” provides more information on seasonal sun angles and their effects on shade design. On the following pages are internet links to more information on skin cancer and its prevention as well as to sun-safety curricula.