Exposure to solar UV radiation is believed to be the major environmental cause of melanoma. However, controversy exists over whether children are particularly susceptible to melanoma initiation compared with adults.
The objective of the study by Pfahlberg et al was to compare the effects of sun exposure—and in particular episodes of sunburn—in childhood with that in adulthood to determine whether a "critical period" exists in early life. The study was designed as a multicenter, case-control study. Participants included 603 histologically confirmed melanoma cases and 627 population controls in 7 European countries. Controls were frequency matched to the cases with respect to sex, age, and ethnic origin. Study subjects were recruited from 1994 through 1997. Exposure to excessive solar UV radiation was defined by memory of number of painful sunburns during childhood (≤15 years) or adulthood (>15 years). Trained personnel interviewed all subjects using a standardized interview schedule. Results were analyzed using logistic regression, adjusted for a variety of possible confounders (recruitment center, ethnic origin, age, and sex). The odds ratios for melanoma after defined numbers of episodes of childhood sunburn (adjusted for adult sunburn) were compared with those for adult sunburn (adjusted for childhood sunburn).