Atopic dermatitis, naevi count and skin cancer risk: A meta-analysis.

Background: The risk of skin malignancy among atopic dermatitis (AD) patients is not well established.
Objective: We reviewed the epidemiological evidence on the association between AD, naevi count, and the risk of cutaneous melanoma and keratinocyte skin cancer (KSC).
Methods: We included all studies that compared the naevi count and the risk of skin cancer (melanoma and/or KSC) between AD patients and unaffected individuals. We calculated summary relative risks (SRRs) and 95% confidence intervals (CI) through random effects models; explored correlates of between-studies heterogeneity using sub-group and sensitivity analysis; and assessed publication bias using a funnel-plot-based approach.
Results: The number of common naevi larger ≥2mm on the whole body was consistently lower among AD patients vs. unaffected individuals when measured by trained health professionals. The risk of melanoma was not increased among AD patients (SRR=0.77, 95%CI 0.44-1.35, I ² =85%). We found a significantly increased risk of basal cell cancer (BCC) (SRR=1.34, 95%CI 1.03-1.75, I ² =24.0%) but not for squamous cell cancer (SRR=1.91, 95% CI 0.74-4.91, I ² =0.0%); however, only a few papers adjusted for phenotypic characteristics and/or sunlight exposure. We found no evidence of publication bias.
Conclusions: AD patients may be at increased BCC risk; however, methodological limitations prevented from drawing definitive conclusions. Despite the lack of strong scientific evidence, AD patients should avoid excessive sun exposure, regularly perform skin self examination, and consult a doctor in case of a suspicious skin lesion.
(Copyright © 2016 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.)