Epigenetic information appears to be an inheritable phenomenon as it is vertically transferred to the daughter cells. The main vehicles of the information are DNA methylation, acetylation of histones, and noncoding RNA species. It has been evidenced that the change in this information can dramatically lead to various cancer phenotypes in a rather sporadic manner. The changes, mostly created by the inefficient and/or malfunctioning DNA- and protein-modifying enzymes, reprogram the transcription of certain groups of genes that challenge tumor suppressor genes and activate proto-oncogenes. On the therapeutic side, significant progress has been made. Some promising means of treatment are now clinically available, while some other means are still in trial. A main body of the basic scientific efforts have understandably focused on the insight of epigenome.