Tumor growth is associated with both epigenetic and genetic aberrations resulting in altered gene expression. Cancer is a leading cause of death worldwide, accounting for 8.2 million deaths in 2012. The most common causes of cancer death are cancers of lung, liver, stomach, colorectal, breast, and esophageal cancer. The estimated new cancer rates for men and women in the United States in 2015 are given, respectively. The involvement of DNA methylation in cancer has been known for years and DNA methyltransferase (DNMT) inhibitor is the first epigenetic-based drug for cancer therapy. Chemotherapy for cancer treatment uses drugs called cytostatics, which means poisonous to cells. The alkylating agents were the first nonhormonal drugs to be used effectively in the treatment of various cancer types. Surgery, chemotherapy, and radiotherapy are commonly used for treatment of breast cancer, but these methods are costly, mostly painful, and possess several side effects.