Different features of IgE, including a high affinity for FcεRI (although CD23 is low affinity, increased binding can be achieved via avidity [8]); lack of inhibitory Fc receptors or patient Fc receptor polymorphisms; and efficient long-lasting tissue surveillance have earmarked this antibody class as a potential powerhouse in the field of cancer therapeutics [2,9]. This evidence concerns the gene FCER2 and cancer.