Relationship between ambient ultraviolet radiation and non‐Hodgkin lymphoma subtypes: A U.S. population‐based study of racial and ethnic groups

Associations between ultraviolet radiation (UVR) exposure and non‐Hodgkin lymphoma (NHL) have been inconsistent, but few studies have examined these associations for specific subtypes or across race/ethnicities. We evaluated the relationship between ambient UVR exposure and subtype‐specific NHL incidence for whites, Hispanics and blacks in the United States for years 2001–2010 (n = 187,778 cases). Incidence rate ratios (IRRs) and 95% confidence intervals (CIs) were calculated for UVR quintiles using Poisson regression. Incidence was lower for the highest UVR quintile for chronic/small lymphocytic/leukemia (CLL/SLL) (IRR = 0.87, 95% CI: 0.77–0.97), mantle cell (IRR = 0.82, 95% CI: 0.69–0.97), lymphoplasmacytic (IRR = 0.58, 95% CI: 0.42–0.80), mucosa‐associated lymphoid tissue (MZLMALT) (IRR = 0.74, 95% CI: 0.60–0.90), follicular (FL) (IRR = 0.76, 95% CI: 0.68–0.86), diffuse large B‐cell (IRR = 0.84, 95% CI: 0.76–0.94;), peripheral T‐cell other (PTCL) (IRR = 0.76, 95% CI: 0.61–0.95) and PTCL not otherwise specified (PNOS) (IRR = 0.77, 95% CI: 0.61–0.98). Trends were significant for MZLMALT, FL, DLBCL, BNOS and PTCL, with FL and DLBCL still significant after Bonferroni correction. We found interaction by race/ethnicity for CLL/SLL, FL, Burkitt, PNOS and MF/SS, with CLL/SLL and FL still significant after Bonferroni correction. Some B‐cell lymphomas (CLL/SLL, FL and Burkitt) suggested significant inverse relationships in whites and Hispanics, but not in blacks. Some T‐cell lymphomas suggested the most reduced risk for the highest quintile of UVR among blacks (PNOS and MF/SS), though trends were not significant. These findings strengthen the case for an inverse association of UVR exposure, support modest heterogeneity between NHL subtypes and suggest some differences by race/ethnicity.