The risk of cancer among patients previously hospitalized for atopic dermatitis.

In treatment of severe atopic dermatitis, drugs with carcinogenic potentials are used to manage the disease. We therefore analyzed whether patients having severe atopic eczema had an increased cancer risk. The study population included all individuals hospitalized in Denmark with a primary diagnosis of atopic dermatitis during 1977-1996. Follow-up was conducted in 1996 in the Danish Cancer Register. A total of 6275 persons were included. Among 2030 adult patients, an increased risk of cancer was observed, standard morbidity ratio (SMR)=1.5 (95% CI: 1.2-1.9). Half the excess cases of cancer was keratinocyte carcinomas of the skin diagnosed within the first 9 y of follow-up, SMR=2.4 (95% CI: 1.4-3.9). For men, SMR=2.7 (95%CI: 1.2-5.4). In conclusion, earlier hospitalized adult atopic dermatitis patients had an increased risk of cancer. Half the excess cases of cancer were keratinocyte carcinomas. This may be a result of a detection bias or due to the carcinogenic potentials of some of the therapies of severe atopic dermatitis.