The characteristics of all somatic cells is their limited life duration and regulated proliferation, differentiation and survival necessary for the organism to function properly. As a result of internal and external factors on the organism, along with inappropriate regulation of control mechanism, the cells receive new biological characteristics, also known as malignant. Tumor cells can duplicate meaning that the tumor acquires an ability for uncontrollable proliferation of cells. The process of carcinogenesis begins as a result of carcinogens that damage DNA and induce mutations and promoters that stimulate the proliferation of cells. In the control of cellular processes, the proteins encoded by genes participate in cancer formation. Oncogenes are genes which stimulate cell division, while tumor suppressor genes inhibit proliferation and control the cell’s life cycle. The objective of this thesis is to explain the properties of tumor cells, their formation, growth, and also to explain genes that are involved in the formation of cancer, approaches to treatment of tumors and the importance of a proper diet, as well as the importance of food as a preventative mean to the formation of tumors.