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ContextHigh nevus density is a risk factor for cutaneous malignant melanoma. Melanocytic nevi originate in childhood and are largely caused by solar exposure.ObjectiveTo determine whether use of broad-spectrum, high–sun protection factor (SPF) sunscreen attenuates development of nevi in white children.DesignRandomized trial conducted June 1993 to May 1996.Setting and ParticipantsA total of 458 Vancouver, British Columbia, schoolchildren in grades 1 and 4 were randomized in 1993. After exclusion of nonwhite children and those lost to follow-up or with missing data, 309 children remained for analysis. Each child's nevi were enumerated at the start and end of the study in 1996.InterventionParents of children randomly assigned to the treatment group (n=222) received a supply of SPF 30 broad-spectrum sunscreen with directions to apply it to exposed sites when the child was expected to be in the sun for 30 minutes or more. Children randomly assigned to the control group (n=236) received no sunscreen and were given no advice about sunscreen use.Main Outcome MeasureNumber of new nevi acquired during the 3 years of the study, compared between treatment and control groups.ResultsChildren in the sunscreen group developed fewer nevi than did children in the control group (median counts, 24 vs 28; P=.048). A significant interaction was detected between freckling and study group, indicating that sunscreen use was much more important for children with freckles than for children without. Modeling of the data suggests that freckled children assigned to a broad-spectrum sunscreen intervention would develop 30% to 40% fewer new nevi than freckled children assigned to the control group.ConclusionsOur data indicate that broad-spectrum sunscreens may attenuate the number of nevi in white children, especially if they have freckles.

Background and Design: Basal cell carcinoma (BCC) of the skin is the most common neoplasm in white populations, and solar radiation is generally accepted to be the dominant environmental risk factor for this disease. However, little information is available on the nature of the relationship between BCC and sunlight. The purpose of this study was to evaluate the nature of the relationship between sunlight exposure, pigmentary factors, and BCC of the skin. A population-based case-control study of 226 male patients with BCC diagnosed from January 1, 1983, through December 31, 1984, and 406 randomly selected male control subjects was conducted in Alberta, Canada. The study was conducted using a standardized questionnaire, administered in person by trained interviewers. Data were analyzed using conditional logistic regression methods. Results: After controlling for other host and pigmentary factors, the risk of BCC was increased in subjects with light skin color and those who freckled in childhood. A history of severe sunburn in childhood also increased risk. Subjects of southern European ethnic origin were at significantly lower risk of BCC. Surprisingly, no association was seen between mean annual cumulative summer sunlight exposure and risk of BCC. A significantly increased risk of BCC was seen in subjects with increased recreational sunlight exposure in adolescence and childhood (age, 0 to 19 years), although an inverse relationship was seen with lifetime recreation exposure. The relationship with childhood sun exposure was most pronounced among sun-sensitive subjects whose skin tended to burn rather than tan in the sun. Conclusions: The lack of association between cumulative sun exposure and BCC contradicts conventional wisdom about the cause of this tumor, and the increased risk with sun exposure at age 0 to 19 years suggests that childhood and adolescence may be critical periods for establishing adult risk for BCC. (Arch Dermatol. 1995;131:157-163)

Introduction and Design: Squamous cell carcinoma of the skin (SCC), a common cancer in white populations, is related to sunshine exposure; however, relatively little information is available on how timing and character of exposure affect the relationship. The purpose of this study was to investigate the nature of the relationship of SCC to individual solar UV exposure after control for phenotype and pigmentary factors. All newly diagnosed cases of SCC were in men aged 25 through 79 years, ascertained in the province of Alberta from January 1, 1983, through December 31, 1984, who were approached for participation; 80% completed a standardized etiologic interview that was conducted in their homes by a trained interviewer. Control subjects were chosen at random from the Alberta Health Care Insurance Plan subscribers list, matched only by sex (male) and age (within a 5-year age group). The response rate among controls was 71%. Results: Subjects with pale skin and red hair had an elevated risk of SCC. Subjects whose mother was of southern European ancestry had a reduced risk of SCC. After accounting for pigmentary factors, no association was seen between risk of SCC and cumulative lifetime sun exposure. However, a strong trend toward increasing risk was seen with increasing chronic occupational sun exposure in the 10 years prior to diagnosis. Conclusion: The results suggest that recent sun exposure (in the 10 years prior to diagnosis) may be important in accounting for individual risk of SCC. (Arch Dermatol. 1995;131:164-169)

• The association between prevalence of benign melanocytic nevi and a number of skin cancer risk factors was examined among 913 white Vancouver (Canada) school children aged 6 to 18 years. Subjects with light skin, with a propensity to burn rather than tan in the sun, and with numerous or severe sunburns in the previous 5 years had significantly higher nevus counts than individuals without these characteristics. Subjects who acquired deeper tans tended to have fewer nevi than those who did not tan. Finally, children who freckled had higher nevus counts than those who did not freckle. These findings in children are similar to those seen in studies of malignant melanoma among adults and suggest that strategies to reduce melanoma incidence should begin with young children. ( Arch Dermatol. 1990;126:770-776)

• The presence of acquired benign nevi is a risk factor for cutaneous melanoma, yet relatively little is known about the etiology of nevi. We have conducted a study of the prevalence of melanocytic nevi among 1146 white Vancouver (Canada) schoolchildren aged 6 to 18 years. Numbers of nevi per square meter of body surface area increase with age in children of both sexes. Male adolescents have more nevi than female adolescents on the head and neck as well as on the trunk, while prevalence in females is higher on the upper and lower limbs. This distribution parallels that of cutaneous melanoma in British Columbia adults. Nevi are more common in children on intermittently exposed body sites than on constantly or minimally sun-exposed sites. This suggests that exposure to strong intermittent sunlight in childhood (a risk factor for cutaneous melanoma) may also be important in the etiology of acquired benign nevi. ( Arch Dermatol . 1990;125:466-471)