Incidence of cancer in the general population and in patients with or without atopic dermatitis in the U.K.

Background Atopic dermatitis (AD) affects approximately 20% of children and 1-3% of adults in developed countries. Objective To study the incidence of cancer in patients with AD in the U. K. general population. Methods We conducted a follow-up study in the U. K. using The Health Improvement Network (THIN) database. We calculated the incidence rate (IR) of the first occurrence of overall cancer, lymphoma, melanoma and nonmelanoma skin cancer (NMSC) in the general population, in patients with AD and in individuals without AD. In addition we calculated the IR ratio (IRR) of overall cancer and subtypes of cancer in patients with AD vs. those without. Results The study population included 4 518 131 patients [2 336 230 (51.7%) female]. There were 129 972 subjects [68 688 (52.8%) female] with a diagnosis of cancer (excluding NMSC). The IR (per 10 000 person-years) of cancer (excluding NMSC) was 42.41 [95% confidence interval (CI) 42.18-42.64]; of lymphoma 1.70 (95% CI 1.65-1.74); of skin melanoma 1.71 (95% CI 1.67-1.76) and of NMSC 11.76 (95% CI 11.64-11.88). The age-and sex-adjusted IRR for cancer (excluding NMSC) was 1.49 (95% CI 1.39-1.61); for lymphoma 2 21 (95% CI 1.65-2.98); for melanoma 1.74 (95% CI 1.25-2.41); and for NMSC 1.46 (95% CI 1.27-1.69). Conclusions Our results indicate an increased incidence of cancer overall as well as of specific cancer subtypes, including lymphoma, in patients with AD. Further studies are needed to disentangle the effects of treatment for AD from AD itself.