Atopic eczema may be associated with lymphoma risk

Atopic eczema carried no association with overall cancer risk but was associated with non-Hodgkin and Hodgkin lymphoma, according to results of two large population-based studies.

“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,” Kathryn E. Mansfield, PhD, of the department of non-communicable disease epidemiology at the London School of Hygiene and Tropical Medicine, and colleagues wrote. “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.”

The current matched cohort study included groups from England and Denmark. There were 471,970 individuals with atopic eczema and 2,239,775 individuals without atopic eczema in the English study. The median age of this group was 41.1 years for the study population and 39.8 years for controls. The atopic eczema arm of the English cohort was 58.6% female, while the arm without atopic eczema was 58.1% female.

The Danish group included 44,945 individuals with atopic eczema and 445,673 individuals without atopic eczema. The median age was 13.7 years for those with atopic eczema and 13.5 years for controls. In both groups, 50.8% of the subjects were female.

The English cohort study was conducted between Jan. 2, 1998, and March 31, 2016, while the Danish cohort ran from Jan. 1, 1982, to June 30, 2016. Data were culled from English primary care and nationwide Danish data.

Overall cancer risk and risk for specific malignancies among individuals with atopic dermatitis and controls served as the main outcome measure.

For the English cohort, the researchers observed no significant association between atopic eczema and overall risk for most specific cancers (adjusted HR = 1.04; 99% CI, 1.02-1.06). This outcome was similar in Denmark (HR = 1.05; 99% CI, 0.95-1.16).

However, in England, atopic eczema carried an association with noncutaneous lymphoma risk, including associations with non-Hodgkin lymphoma (HR = 1.19; 99% CI, 1.07-1.34) and Hodgkin lymphoma (HR = 1.48; 99% CI, 1.07-2.04).

Moreover, increased severity of atopic eczema increased lymphoma risk. Compared with controls, individuals with mild eczema had a lower risk for non-Hodgkin lymphoma (HR = 1.06; 99% CI, 0.90-1.25) than those with moderate (HR = 1.24; 99% CI, 1.04-1.48) or severe (HR = 2.08; 99% CI, 1.42-3.04) eczema.

Similarly, analysis of the Danish cohort showed that, compared with no atopic eczema, individuals with moderate to severe eczema were at increased risk for non-Hodgkin lymphoma (minimally adjusted HR = 1.31; 99% CI, 0.76-2.26) and Hodgkin lymphoma (minimally adjusted HR = 1.35; 99% CI, 0.65-2.82).

“The findings from two large population-based studies performed in different settings do not support associations between atopic eczema and most cancers,” the researchers wrote. “However, an association was observed between atopic eczema and lymphoma, particularly [non-Hodgkin lymphoma], that increased with eczema severity. This finding warrants further study as new immunomodulatory systemic therapeutics are brought to market that may alter cancer risk.”