Early-life sun exposure and risk of melanoma before age 40 years

To examine associations between early-life sun exposure and risk of invasive cutaneous melanoma diagnosed between ages 18 and 39 years.

Data were analysed from 606 cases and 481 controls from the Australian Melanoma Family Study, a population-based, case-control-family study. Self- and parent-reported sun exposure was collected by interview. Odds ratios (OR) were estimated using unconditional logistic regression, adjusted for potential confounders.

Self-reported childhood total sun exposure was not associated with melanoma overall, but was positively associated with melanoma diagnosed at 18-29 years of age (OR for highest vs. lowest quartile: 3.21, 95% confidence intervals (CI) 1.38-7.44; P (trend) 0.02; P (interaction) by age group 0.09). Analyses restricted to participants whose self-reported sun exposure was concordant with that recalled by their parents gave an OR for the highest versus lowest tertile of childhood total sun exposure of 2.28 (95% CI 1.03-5.04; P (trend) 0.05), and for any versus no severe childhood sunburn of 2.36 (95% CI 1.05-5.31). The association of self-reported severe sunburn with melanoma was evident only in people who tended to tan rather than burn and in people who had few nevi.

The association of early-life sun exposure with early-onset melanoma is influenced by host factors.