What causes cancer?

What causes cancer?

Cancer is essentially the result of non-lethal genetic damage to cells (mutations in cellular DNA). Causes of such mutations include radiation, chemicals, hormones and infections. Some damage to cellular DNA is a daily "wear and tear" event, and all mammals have many safeguards to prevent or repair such damage. Nonetheless, such protective mechanisms are not flawless. In some individuals there are even defects in such defences, resulting in a higher than expected occurrence of cancer. Some of those defects in protection are inherited; for example, some purebred dogs have inherited predispositions to develop specific forms of cancer. In other instances, the protective mechanisms are unable to cope with excessive injury.

The mutated DNA upsets the normal regulation of cell growth, and the "altered" cells no longer obey the rules governing coordinated cell activity, instead growing in an uncontrolled and uncoordinated fashion.