Cancer as a Genetic or Epigenetic Disease?

Genetic analysis of cancer suggests that neoplastic cells arise through an accumulation of mutations. The introduction of sequences of mutations increase the casual complexity associated with tumor progression. The disruption of tissue architecture is the critical causal event in tumor progression, while mutations are a consequence of this disruption. The tumor microenvironment provides continuous biochemical and mechanical feedback to resident cells within the vicinity of tumor cells, and evidence suggests that this milieu can promote or restrict metastatic progression, and the success of colonization of a secondary site depends on the early establishment of a "premetastatic niche," i.e., a local environment that is favorable for the seeding of circulating cancer cells.