[Chemoprevention of colorectal cancer].

Gastrointestinal cancer poses a major clinical challenge in the developed world where the disease is common. Cancer chemoprevention is defined as the use of natural, synthetic or chemical agents to reverse, suppress or prevent carcinogenic progression to invasive cancer. The success of several clinical trials in preventing cancer in high-risk populations suggests that chemoprevention can be rational strategy. Besides, in population-based observational studies, people had lower rates of colorectal cancer if they were taking various agents, including nonsteroidal anti-inflammatory drugs, calcium, folate. Cyclooxygenase-2 inhibitors and NSAIDs reduce the incidence of colonic adenomas. However, these agents are associated with important cardiovascular events and gastrointestinal harms. Contemporary, the balance of benefits to risk does not favor chemoprevention in average-risk individualse.