This information is not all mine but this is what I have found.
The DNA double strand is wrapped around a protien complex. To ensure that basic processes such as DNA replication during cell division or the translation of genetic information into proteins is able to take place without problems, enzymes need to have free access to genetic information. Therefore, it is vital that the genetic material can be converted back from its compact form into a form that is easier to access. To make this happen, the cell regulates the binding of DNA to the protiens through chemical changes in the protiens themselves. In this way, these changes influence both the structure of the genetic material and the cell function. Since activation and silencing of genes or oncogenes also depend on the extent of packaging, these chemical changes are believed to play a central role in the transformation of a normal cell into a cancer cell.
Now I believe that this change in the DNA is much helpful to most people who have cancer and need a remedy.