Atopic dermatitis patients may have increased risk of malignancies

February 1, 2008

Patients suffering from atopic dermatitis seem to be at an increased risk of developing malignancies, including lymphoma and cutaneous melanoma, as well as nonmelanoma skin cancers, when compared with patients who do not suffer from the disease, according to a recent large database-controlled study

Key Points

International report - The burden of disease can be significant in patients suffering from atopic dermatitis, with approximately 20 percent of children and 1 percent to 3 percent of adults in developed countries being affected by this dermatologic disorder.

Adding insult to injury, these patients may have an increased risk of developing malignancies, such as lymphoma, as well as cutaneous melanoma and nonmelanoma skin cancers, according to a recent study.

Felix Arellano, M.D., of Risk Management Resources España, S.L., in Zaragoza, Spain, and Bridgewater, Conn., and a team of researchers from Spain, Switzerland and the United States reported on the results of a study of atopic dermatitis patients in England.

The study looked at the cancer rates in general, as well as the incidence rates of lymphoma, melanoma and nonmelanoma skin cancer in both patient populations.

Of the 4,456,008 patients included in the study, 232,309 patients, or 5.2 percent, suffered from atopic dermatitis. Results showed that 129,972 patients, of whom approximately half were female, were found to have a diagnosis of cancer, excluding non-melanoma skin cancer.

The incidence rates of overall cancer (excluding nonmelanoma skin cancer), lymphoma, melanoma and nonmelanoma skin cancer were found to be 42.41, 1.70, 1.72 and 11.69 per 10,000 person years, respectively, in patients suffering from atopic dermatitis.

Dr. Arellano noticed that the incidence rate increased with age, particularly in the female study population, although, in general, it was higher in males than in females in each age stratum.

"The results of our study suggest that there is an overall increased risk of cancer, as well as an increased risk of cancer subtypes, including lymphoma, in patients suffering from atopic dermatitis.

"These results should move not only dermatologists, but all medical professionals, to more closely watch and follow their patients who are suffering from atopic dermatitis, as their increased risk in developing an array of cancers appears to be increased," Dr. Arellano says.

According to Dr. Arellano, a possible theory as to why atopic dermatitis patients apparently have an increased risk of developing malignancies is that the chronic stimulation of the immune system by an antigen possibly induces the development of random pro-oncogenic mutations, which can lead to an increase in cancer development.

"The small differences seen in overall cancer could be attributed to the fact that in our study, only first occurrence of cancer was taken into consideration compared to any occurrence, or to small differences in the age distributions.

"However, in the case of melanoma, we should consider that there was a possible degree of under-reporting in the standard cancer registries," Dr. Arellano says.

Overall, Dr. Arellano noticed approximately a 40 percent increase in cancer risk - including lymphoma, cutaneous melanoma and nonmelanoma skin cancers - for patients with atopic dermatitis, compared with those without the disease.

According to Dr. Arellano, the finding that melanoma rates were higher in atopic individuals was surprising, as atopic dermatitis is associated with a decrease in the number of melanocytic nevi.

"The increased risk of melanoma in atopic patients could be explained if other determinants of melanoma, such as skin type, eye and hair color, history of sunburns, as well as a family history of melanoma were also taken into consideration in our study.

"Since these were not, I believe these results should be interpreted with caution, and a possible association between atopic dermatitis and melanoma should be explored in further analytic studies with full control of risk factors for melanoma, and validation of the diagnosis of melanoma," Dr. Arellano says.

Disclosure: The study was funded by an unrestricted grant from Novartis Pharmaceuticals.