Prospective pooled analyses of ambient ultraviolet radiation levels and risk of non-Hodgkin lymphoma and multiple myeloma

Case-control studies of sun exposure and ultraviolet radiation (UVR) have consistently reported inverse associations with non-Hodgkin lymphoma (NHL) risk, but prospective studies have yielded mixed results. Few studies have explored these exposures in relation to multiple myeloma (MM) risk. To further evaluate these associations with NHL and MM risk and identify etiologically relevant exposure timing, we pooled data on 566,693 individuals from 6 United States (U.S.) prospective cohort studies (11,636 incident NHL; 2,749 incident MM; median follow-up: 20 years) and used geographic information systems models to estimate residential ambient UVR levels at time points from birth to adulthood. Using Cox proportional hazards models, we calculated hazard ratios (HRs) and 95% confidence intervals (CI) for associations of residential ambient UVR levels with NHL overall, NHL subtypes, and MM, adjusted for study, age and other putative risk factors. No UVR measures were significantly associated with NHL or NHL subtypes. Higher residential UVR levels during cohort follow-up were inversely associated with MM overall and among females (longitudinally-updated HR per interquartile range increase: 0.74; 95% CI: 0.63, 0.86) but not males (1.08; 0.90, 1.29). Our results do not confirm an inverse association of adult ambient UVR levels with NHL risk. The MM findings require further investigation.