Tehran University of Medical Sciences Immunology and Genetics Journal 2645-4831 4 4 2021 12 22 171 185 Sara Hemmati School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Behnoud Baradaran Noveiry Cancer Immunology Project (CIP), Universal Scientific Education of Research Network (USERN), CT, USA Mahsa Keshavarz-Fathi School of Medicine, Tehran University of Medical Sciences, Tehran, Iran 2022 09 25 2022 10 10 Both innate and adaptive arms of immune system play role in tumor development. Moreover, genetic and epigenetic alterations, widely demonstrated in cancer cells, result in disturbances in molecular pathways regulating cell growth, survival, and metastasis. Knowledge of molecular and cellular mechanisms involved in carcinogenesis leads to improvement of targeted treatments for cancers. Similarly, allergies are immune related entities and are treated according to the molecular mechanisms of hypersensitivity reactions. Some studies support the hypothesis of inverse association between cancer and susceptibility for allergies but the correlation is not simple and some demonstrate positive relation. For example, in some studies histamine released in response to allergens plays a role in tumor progression, probably through maintaining survival of myeloid derived suppressor cells (MDSCs). However, in other studies, the protective role of IgE against carcinogenesis have been reported. In this review, the role of immune system and specific molecular mechanisms in cancer and allergy will be discussed. Based on separately mentioned factors, interactions between these two seemingly disparate entities will also be presented. We conducted this review to illustrate potential molecular and cellular mechanisms underlying the association of cancer and allergy and make a basis for future interventions. https://igj.tums.ac.ir/index.php/igj/article/view/104