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 ≥2 mm 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, I² = 85%). We found a significantly increased risk of basal cell cancer (BCC) (SRR = 1.34, 95%CI 1.03–1.75, I² = 24.0%) but not for squamous cell cancer (SRR = 1.91, 95% CI 0.74–4.91, I² = 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.