These errors can give rise to mutations or epigenetic alterations.

However, it has become apparent that cancer is also driven by epigenetic alterations.

Mutations, however, may not be as frequent in cancers as epigenetic alterations.

However, by comparison, epigenetic alterations appear to be more frequent in colon cancers.

Thus, epigenetic alterations are a major source of changes in gene expression, important in cancer.

This process is called differentiation, through epigenetic and regulatory alterations.

It would also be expected that many of the epigenetic alterations present in tumors may have occurred in pre-neoplastic field defects.

Such field defects (second level from bottom of figure) may have multiple mutations and epigenetic alterations.

Likewise, epigenetic alterations present in tumors may have occurred in pre-neoplastic field defects.

A somatic epitype is a non-heritable epigenetic alteration in a gene.