Relationship between ambient ultraviolet radiation and Hodgkin lymphoma subtypes in the United States

There are few modifiable risk factors for Hodgkin lymphoma (HL), the most common cancer among young adults in Western populations. Some studies have found a reduced risk with exposure to ultraviolet radiation (UVR), but findings have been inconsistent and limited to HL as a group or the most common subtypes.

We evaluated UVR and incidence of HL subtypes using data from 15 population-based cancer registries in the United States from 2001 to 2010 (n=20 021). Ground-based ambient UVR estimates were linked to county of diagnosis. Incidence rate ratios (IRRs) and 95% confidence intervals (CIs) were calculated for UVR quintiles using Poisson regression models adjusted for age, sex, race/ethnicity, diagnosis year, and registry.

Hodgkin lymphoma incidence was lower in the highest UVR quintile for nodular sclerosis (IRR=0.84, 95% CI=0.75-0.96, P-trend<0.01), mixed cellularity/lymphocyte-depleted (IRR=0.66, 95% CI=0.51-0.86, P-trend=0.11), lymphocyte-rich (IRR=0.71, 95% CI=0.57-0.88, P-trend<0.01), and nodular lymphocyte predominant HL (IRR=0.74, 95% CI=0.56-0.97, P-trend<0.01), but 'not otherwise specified' HL (IRR=1.19, 95% CI=0.96-1.47, P-trend=0.11).

This is the largest study of UVR and HL subtypes covering a wide range of UVR levels; however, we lack information on personal UVR and other individual risk factors. These findings support an inverse association between UVR and HL.