Allergic diseases and malignancies cause a lot of morbidity, mortality and high costs for healthcare systems. An inverse association between allergy and cancer has been suspected for a long time, but even despite extensive research no general relationship has been determined. This review comprises 32 epidemiological studies published between 1960 and 2011 and draws conclusions regarding relationships between specific types of cancer and allergic diseases. On the one hand, inflammatory reactions in the course of allergy can support carcinogenesis but are limited to specific areas, whereas on the other hand systemic effects in terms of enhanced immunosurveillance can prevent cancer.