American Society of Hematology, Blood, 20(122), p. 3492-3499, 2013
DOI: 10.1182/blood-2013-04-497586
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Ultraviolet radiation (UVR) exposure has been inversely associated with Hodgkin lymphoma (HL) risk but inconsistently, in few studies, and without attention to HL heterogeneity. We conducted a pooled analysis of HL risk focusing on type and timing of UVR exposure, and on disease subtypes by age, histology, and tumor-cell Epstein-Barr virus (EBV) status. Four case-control studies contributed 1,320 HL cases and 6,381 controls. We estimated lifetime, adulthood, and childhood UVR exposure and history of sunburn and sunlamp use. We used two-stage estimation with mixed-effects models and weighted pooled effect estimates by inverse marginal variances. We observed statistically significant inverse associations with HL risk for UVR exposures during childhood and adulthood, sunburn history, and sunlamp use, but found no significant dose-response relationships. Risks were significant only for EBV-positive HL (pooled odds ratio = 0.56, 95% confidence interval = 0.35, 0.91 for the highest overall UVR exposure category), with a significant linear trend for overall exposure (p=0.03). Pooled relative risk estimates were not heterogeneous across studies. Increased UVR exposure may protect against HL, particularly EBV-positive HL. Plausible mechanisms involving UVR induction of regulatory T cells or the cellular DNA damage response suggest opportunities for new prevention targets.