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Broad-Spectrum Sunscreen Use and the Development of New Nevi in White Children a Randomized Controlled Trial

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Broad-Spectrum Sunscreen Use and the Development of New Nevi in White Children a Randomized Controlled Trial ORIGINAL CONTRIBUTION Broad-Spectrum Sunscreen Use and the Development of New Nevi in White Children A Randomized Controlled Trial Richard P. Gallagher, MA Context High nevus density is a risk factor for cutaneous malignant melanoma. Me- Jason K. Rivers, MD, FRCPC lanocytic nevi originate in childhood and are largely caused by solar exposure. Tim K. Lee, MSc Objective To determine whether use of broad-spectrum, high–sun protection fac- tor (SPF) sunscreen attenuates development of nevi in white children. Chris D. Bajdik, MMath Design Randomized trial conducted June 1993 to May 1996. David I. McLean, MD, FRCPC Setting and Participants A total of 458 Vancouver, British Columbia, schoolchil- Andrew J. Coldman, PhD dren in grades 1 and 4 were randomized in 1993. After exclusion of nonwhite chil- dren and those lost to follow-up or with missing data, 309 children remained for analy- STRONG RISK FACTOR FOR THE sis. Each child’s nevi were enumerated at the start and end of the study in 1996. development of cutaneous malignant melanoma (CMM) Intervention Parents 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 in white populations is the exposed sites when the child was expected to be in the sun for 30 minutes or more. Apresence of acquired melanocytic Children randomly assigned to the control group (n=236) received no sunscreen and 1-4 nevi. There is a consistent rise in risk were given no advice about sunscreen use. of CMM with increasing number of nevi Main Outcome Measure Number of new nevi acquired during the 3 years of the in virtually every study that has as- study, compared between treatment and control groups. sessed this relationship.3-6 The pres- ence of remnants of preexisting nevi Results Children in the sunscreen group developed fewer nevi than did children in 7 the control group (median counts, 24 vs 28; P=.048). A significant interaction was in about 50% of CMMs indicates that detected between freckling and study group, indicating that sunscreen use was much acquired nevi are precursor lesions more important for children with freckles than for children without. Modeling of the 8,9 for many, although not all, mela- data suggests that freckled children assigned to a broad-spectrum sunscreen inter- nomas.9 vention would develop 30% to 40% fewer new nevi than freckled children assigned Recent work has focused on the ori- to the control group. gin and etiology of nevi in children, who Conclusions Our data indicate that broad-spectrum sunscreens may attenuate the are, for the most part, born without number of nevi in white children, especially if they have freckles. nevi. Fewer than 2% of children have JAMA. 2000;283:2955-2960 www.jama.com a congenital nevus,10,11 although ac- quired nevi begin to become clinically velopment of acquired nevi is sunlight With this in mind, we have conducted obvious at an early age.12 Etiologic stud- exposure as measured by sunburn his- a randomized controlled trial to see ies have shown that host and pigmen- tory,13 latitude of residence,19 or re- whether broad-spectrum high–sun pro- tary characteristics (eg, light skin color, ported solar exposure.14,16 tection factor (SPF) sunscreen use freckling, propensity to burn in the sun) Reducing acquired nevi in children might attenuate the number of new nevi that raise adult risk of CMM also pre- may reduce their risk of CMM as adults. that develop in white children. dispose children to develop high ne- vus density.13-16 Genetic factors also in- Author Affiliations: Cancer Control Research Pro- Columbia (Mr Gallagher and Drs Rivers and McLean), gram, British Columbia Cancer Agency (Messrs Gal- Vancouver. fluence nevus prevalence, with higher lagher, Lee, and Bajdik and Dr Coldman), Depart- Corresponding Author and Reprints: Richard P. Gal- counts of melanocytic nevi in mela- ment of Health Care and Epidemiology, University of lagher, MA, Cancer Control Research Program, Brit- 17,18 British Columbia (Messrs Gallagher and Bajdik), Divi- ish Columbia Cancer Agency, 600 W Tenth Ave, Van- noma-prone families. The princi- sions of Dermatology, British Columbia Cancer Agency, couver, British Columbia, Canada V5Z 4E6 (e-mail: pal environmental risk factor for the de- Vancouver Hospital, and University of British [email protected]). ©2000 American Medical Association. All rights reserved. (Reprinted) JAMA, June 14, 2000—Vol 283, No. 22 2955 SUNSCREEN USE AND DEVELOPMENT OF NEW NEVI MATERIALS AND METHODS to the sunscreen group received a bottle counted by 2 of the 3 physicians and of SPF 30 broad-spectrum sunscreen 17 (4%) were counted by all 3 physi- Study Design and Data Collection near the end of each school year in June cians. Assuming the variance among the The study was approved by the British 1993, 1994, and 1995. Parents were in- duplicate and triplicate counts was typi- Columbia Cancer Agency and Univer- structed to apply the sunscreen in cal, the proportion of variance in whole- sity of British Columbia research eth- amounts they usually used to all sun- body nevus counts attributable to the ics committees. Six Vancouver elemen- exposed sites on the enrolled child effect of the counter was less than 5%. tary schools with the largest proportion whenever he/she was expected to be in Data were used only if students com- of white children were selected for the the sun for 30 minutes or more. Par- pleted the whole protocol, defined as study. School principals were ap- ents were specifically asked to use the the intake and exit nevus counts, the proached for permission to conduct the particular bottle of sunscreen only on intake questionnaire, and at least 2 of study within their schools. After secur- the enrolled child. At the end of July the 3 summer sun update, Christmas ing permission from the Vancouver each year, a second bottle of sun- break, and spring break question- School Board, the principals released screen was sent. Parents were then naires. If 1 of the summer sun updates names of all children in grades 1 and 4 asked to measure and report how much was not completed, mean values from (aged 6-7 and 9-10 years, respec- of the original bottle had been used by the other 2 such questionnaires were tively) and their parents to the study. marking what remained in the first substituted. The same procedure was Parents were sent a letter explaining the bottle on an actual-size diagram of the followed for missing Christmas and study and were asked for written per- sunscreen bottle. Parents were in- spring break questionnaires. mission to examine each child and en- structed to use the second bottle of sun- roll the child and a parent in the 3-year screen on the index child for the re- Data Analysis investigation. mainder of the summer and the next It is customary in clinical trials to con- At enrollment, each student was ex- Christmas and spring breaks. Parents duct an analysis based on intent-to- amined by either a dermatologist whose children were randomized to the treat. In this study, no intermediate (J.K.R.) known for his expertise in control group were given no advice as nevus counts were taken between ran- childhood nevus studies19-21 or by a phy- to sunscreen use, and no placebo was domization and conclusion. It is there- sician specially trained by him. All nevi, provided. Because of the level of gen- fore not possible to conduct an intent- regardless of size, were counted using eral education about sun exposure, to-treat analysis based on imputed techniques outlined in the Interna- however, use of sunscreen was sub- end-point values for subjects who were tional Agency for Research on Cancer stantial in the control group. lost to follow-up during the course of counting protocol.21 The scalp, geni- At the end of each summer vaca- the study. tal area, and buttocks were not exam- tion, solar exposure during the previ- Several measures of sun exposure ined, nor was the breast area in girls. ous 3 months was determined for chil- were calculated. Minimal erythemal Degree of freckling on the face, dren in each study group using an dose (MED) information for clear sky shoulders, and arms was estimated us- activity-based questionnaire. Cloth- conditions by latitude and month of the ing a chart13 with good observer repro- ing preference and sunscreen use dur- year were obtained from Diffey and El- ducibility. Height and weight of each ing outdoor activities were assessed on wood.23 Vacation solar exposure in child were taken to allow calculation a semiquantitative basis. Similar instru- MEDs during the 3 years was assessed of body surface area.22 Skin reflec- ments were used to evaluate solar ex- using location, latitude, and month of tance on a non–sun-exposed site (up- posure during the Christmas and spring the vacation, assuming that vacation ex- per inner arm) was measured using a breaks each year. As Vancouver is a rela- posure took place during peak, day- reflectance spectrophotometer set to tively low-sunlight area and records light UV-B exposure hours. Total UV 680 nm. Parents of each child com- high temperatures only in the sum- exposure from vacation and recre- pleted a detailed questionnaire, assess- mer, evaluating summer exposure plus ational activities in MEDs, adjusted for ing the child’s ethnic origin, sun sen- the other 2 school holiday periods each clothing worn while outdoors, was also sitivity, sunburn history, and holiday year captures most solar exposure in calculated by anatomic subsite.
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