Traditionally, cancer has been considered a genetic disease due to gene mutations, sporadic or inherited. It is now becoming apparent that it is induced by epigenetic changes, such as the suppression of DNA-repairing genes, the activation of tumor-promoting genes (oncogenes), and the inactivation of tumor-suppressing genes. This has led to a deeper understanding of the molecular pathways that govern the development of cancer as well as improvements in the diagnosis and prediction of the outcome of various types of cancer. Studies of epigenetic regulation mechanisms have led to the identification of new targets that may be useful in developing new strategies for cancer prevention and treatment. Other research has shown that both diet and many supplements act as epigenetic factors against the development of cancer.