The potential for malignancy from atopic disorders and allergic inflammation: A systematic review and meta-analysis.

While chronic inflammation is a well-established risk factor for malignancy, studies evaluating the relationship between allergic inflammation and cancer have revealed conflicting results. Here, we aimed to assess the association between allergic inflammation in the lung (asthma), skin (eczema) or esophagus (eosinophilic esophagitis; EoE) and cancer at the organ site.We conducted a systematic review of the literature to identify observational studies (case-control, cohort, and cross-sectional) evaluating the association between asthma and lung cancer, eczema and skin cancer, or EoE and esophageal cancer. Random-effects meta-analysis was performed to define pooled estimates of effects.PubMED, EMBASE, and Web of Science ELIGIBILITY CRITERIA FOR SELECTION: Included studies evaluated the incidence of cancer.Thirty-two studies met the inclusion criteria, 27 in the lung, 4 in the skin, and 1 in the esophagus. Metanalysis of the 3 studies with prospective data collection of asthma diagnosis revealed a positive association with incident lung cancer (OR 1.27, 95% CI 1.09-1.44); however, this result was not consistently supported by the larger dataset of retrospective studies (OR 1.37, 95%CI 0.90-1.83). Overall, studies in the lung displayed significant heterogeneity (I 98%, p<0.0001), but no significant effect-modification on the association between asthma and lung cancer was identified for the variables of sex, smoking, or study design. Meta-analysis could not be applied to the 4 papers reviewed in the skin, but 3 suggested an association between eczema and non-melanoma skin cancer, while the remaining study failed to identify an association between melanoma and eczema. A single study meeting inclusion criteria showed no association between EoE and esophageal malignancy.The current data cannot exclude the possibility of an association between atopy and malignancy the lung, skin and esophagus. The relationship between allergy and cancer should be explored further in prospective studies that any association identified between these conditions has the potential for significant public health implications.