High Birth Weight, Early UV Exposure, and Melanoma Risk in Children, Adolescents, and Young Adults

Background: Melanoma, the deadliest form of skin cancer, is the second most common cancer diagnosed before age 30. Little is known about potentially modifiable or intervenable risk factors specific to developing melanoma at a young age. The objective was to determine if high birth weight or higher early-life ultraviolet (UV) radiation exposure would be associated with increased risk of melanoma in young patients. Methods: Population-based, case-control study of 1,396 cases of melanoma diagnosed before age 30 in 1988-2013 and 27,920 controls, obtained by linking cancer registry data to birth records in California. Results: High birth weight (>4,000 g) was associated with 19% higher risk of melanoma (OR = 1.19; 95% CI = 1.02, 1.39), while low birth weight (<2,500 g) was associated with 41% lower risk (OR = 0.59; 95% CI = 0.43, 0.82), compared with normal birth weight (2,500-4,000 g); dose-response per 1,000 g increase was also evident (OR = 1.24; 95% CI = 1.13, 1.36). All quartiles of birthplace UV greater than the lowest quartile were associated with increased melanoma risk. The strongest relation between birthplace UV and melanoma was for 15-19 years of age at diagnosis. Conclusions: High birth weight and high early-life UV exposure may be important independent risk factors for melanoma diagnosis before age 30. The implication is that adopting skin-protective behaviors as early as infancy could be important for primary prevention of melanoma in younger people. However, research that accounts for early-life behavioral patterns of skin protection during infancy is needed to advance our understanding of how birth weight and early-life UV may influence the development of early-onset melanoma.