The role of the immune system is to protect the body by eliminating harmful substances and invading microorganisms. Its ability to do so is called immunity which can be divided into two types: innate and adaptive. The main attribute of innate immunity is the ability to swiftly respond to a wide range of pathogens, whereas adaptive immunity forms its response via the production of antibodies and cells that are specifically developed to recognize certain antigens and destroy their carriers. By coming together they interfere with the tumor development. Tumors are clusters of immortal cells which have acquired the ability of infinite growth. The success of their development lies in their proficiency in the manipulation of their microenvironment. The role of the tumor microenvironment is presented in the hypothesis of cancer immunoediting, which is divided into three phases: elimination phase, equilibrium state, and tumor escape phase. The immunosuppressive conditions of the microenvironment that are imposed by cancer cells and their recruited cells facilitate tumor escape by activating or changing various signaling pathways which allow them further mitigation of the immune response. By establishing sheer dominance over the surrounding tissue the tumor ensures the conditions fit for the invasion.