Ambient UVB and Melanoma Risk in the United States: A Case-Control Analysis

Purpose Exposure to ultraviolet-B (UVB) radiation is a well-established risk factor for human cutaneous malignant melanoma. Intermittent and cumulative exposures from UVB have been estimated most often by interview questionnaire. This study assessed cumulative UVB using a ground-based measurement instrument to estimate the association between UVB and melanoma. Methods Population-based, incident cases of melanoma (n = 380) and frequency-matched controls (n = 364) residing in Connecticut at diagnosis were interviewed between 1987 and 1989 about recreational and vacation activities, sun-protection practices, occupation, and other factors. Using a residential history, regression estimates of lifetime UVB were derived from ambient measures of UVB, adjusted for intermittent exposure. Results Cases and controls received 29% of lifetime mean UVB in the first 15 years of life. Number of days per year in recreational activity during childhood and late adulthood were associated with increased melanoma risk. When estimating lifetime UVB adjusted for intermittent exposure, melanoma risk peaked at a 5.7-fold increased risk in the ninth decile. Conclusion Sporadic and chronic sun exposure play a role in melanoma etiology. Skin-protection practices should be encouraged across levels of sun intensity, not only in childhood but throughout adulthood.