Abstract
BACKGROUND: Melanoma incidence has been dramatically increasing worldwide. Psoralen, a known photocarcinogen, is naturally abundant in citrus products, leading to the hypothesis that high citrus consumption may increase melanoma risk. OBJECTIVES: To investigate the association between total citrus consumption and melanoma risk, and the association between individual citrus products and melanoma risk, and to test for interactions between total citrus intake and established melanoma risk factors. METHODS: Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between citrus consumption and melanoma risk among 1592 cases and 197 372 controls from the UK Biobank cohort. Citrus consumption data were collected via five rounds of 24-h recall questionnaires. International Classification of Diseases codes were used to determine melanoma outcome. RESULTS: After adjusting for potential confounders, participants in the highest category of total citrus intake (> 2 servings per day) had a significantly increased risk of melanoma (OR 1·63, 95% CI 1·24-2·12) relative to those with no consumption. For individual citrus products, participants with the most orange and orange juice consumption (> 1 serving per day) had a significantly increased melanoma risk relative to those with no consumption (OR 1·79, 95% CI 1·07-2·78 and OR 1·54, 95% CI 1·10-2·10, respectively). Fair- or very fair-skinned participants with high citrus consumption had an even greater melanoma risk (OR 1·75, 95% CI 1·31-2·29). CONCLUSIONS: High citrus consumption was associated with an increased risk of melanoma in a large, prospective, population-based cohort. Further validation of these findings could lead to improved melanoma prevention strategies.