Colorectal cancer--time as the most important carcinogen: a risky hypothesis about risk

The likelihood of having cancer increases proportionally with a constant power of age, beginning at 25 years old. An equation has been proposed that reproduces this incidence-age relationship, but until now the explanation remains unknown. In this paper, a hypothesis is presented in which tumoral development in human colon and rectum would be the consequence of having exceeded the 'limit number' of mitoses that every stem cell undertakes, from its origin until exhausting the security mechanisms that control the correct replication of genome. The age of cancer appearance would depend on the epithelial turnover time which basically responds to a genetic control.