Adaptive mutagenesis--cause of alimentary cancer?

The tissues of the alimentary tract react to abnormal functional demands or to injury from environmental chemicals by reactions which involve change in morphology, functional characteristics and cellular proliferation. The work hyperplasia, wound repair or response to xenobiotics may become distorted by inherent, or induced, genomic abnormalities of the affected cells. It seems that some of the reactions are 'programmed' or 'planned' and depend on predetermined changes in gene expression. Although the reactions permit survival in the face of environmental hazards, the necessary alterations in gene expression may predispose to malignant change in the affected cells.