Iron Deficiency Anemia (IDA) is a universal health problem and a risk factor for the development of cancer. IDA changes the microenvironment of the human body by affecting both the biological and immunological systems. It increases DNA damage and genomic instability by different mechanisms. IDA is one of the leading causes of the imbalance between different antioxidant enzymes as well as enzymes involved in DNA damage and DNA repair systems of the body. It can affect the biogenesis/expression of microRNAs. IDA interrupts the oxidative phosphorylation energy metabolism and intestinal Cytochrome-P450 systems. It also disturbs multicellular signaling pathways involved in cell survival and helps in tumor angiogenesis. Moreover, IDA is also responsible for the functional deterioration of innate and adaptive immune systems that lead to immunological dysfunctions against invading pathogens. Genomic instability and immunological dysfunctions are the hallmarks of cancer development. In this review, we will review the evidence linking IDA to increased cancer risk.