Associations between atopic eczema and cancer are unclear, with competing theories that increased immune surveillance decreases cancer risk and that immune stimulation increases cancer risk. Establishing baseline cancer risk in people with atopic eczema is important before exploring the association between new biologic drugs for atopic eczema and cancer risk..
..In England, matched cohorts included 471 970 individuals with atopic eczema (median [IQR] age, 41.1 [24.9-60.7] years; 276 510 [58.6%] female) and 2 239 775 individuals without atopic eczema (median [IQR] age, 39.8 [25.9-58.4] years; 1 301 074 [58.1%] female). In Denmark, matched cohorts included 44 945 individuals with atopic eczema (median [IQR] age, 13.7 [1.7-21.1] years; 22 826 [50.8%] female) and 445 673 individuals without atopic eczema (median [IQR] age, 13.5 [1.7-20.8] years; 226 323 [50.8%] female).
Little evidence was found of associations between atopic eczema and overall cancer (adjusted hazard ratio [HR], 1.04; 99% CI, 1.02-1.06 in England and 1.05; 99% CI, 0.95-1.16 in Denmark) or for most specific cancers. However, noncutaneous lymphoma risk was increased in people with atopic eczema in England (adjusted HR, 1.19; 99% CI, 1.07-1.34 for non-Hodgkin lymphoma [NHL] and 1.48; 99% CI, 1.07-2.04 for Hodgkin lymphoma).
Lymphoma risk was increased in people with greater eczema severity vs those without atopic eczema (NHL adjusted HR, 1.06; 99% CI, 0.90-1.25 for mild eczema; 1.24; 99% CI, 1.04-1.48 for moderate eczema; and 2.08; 99% CI, 1.42-3.04 for severe eczema). Danish point estimates also showed increased lymphoma risk in people with moderate to severe eczema compared with those without atopic eczema (minimally adjusted HR, 1.31; 99% CI, 0.76-2.26 for NHL and 1.35; 99% CI, 0.65-2.82 for Hodgkin lymphoma), but the 99% CIs were wide.
Conclusions and Relevance The findings from 2 large population-based studies performed in different settings do not support associations between atopic eczema and most cancers. However, an association was observed between atopic eczema and lymphoma, particularly NHL, that increased with eczema severity. This finding warrants further study as new immunomodulatory systemic therapeutics are brought to market that may alter cancer risk.