Epidemiology, treatment and chemoprevention in colorectal cancer.

In Western countries, colorectal cancer (CRC) is second only to cancer of the lung as a cause of death from malignancy, and affects perhaps one in 20 of the population. In the pre-chemotherapy era, advances in surgery and earlier presentation led to some improvement in survival. However, no more than 60% of CRC patients can expect to be alive at 5 years. Adjuvant chemotherapy in stage III disease is of proven benefit. In metastatic CRC, chemotherapy extends disease-free and overall survival compared with best supportive care alone, and improves quality of life. In palliation, infusional 5-fluorouracil (5-FU) is more active than bolus regimens and is less toxic. Several new cytotoxic agents show promise in CRC. Notable among them is irinotecan, which extends survival both when used as a single agent second-line versus best supportive care alone, and when added to 5-FU/folinic acid in the first-line setting. Much CRC is familial, raising the prospect of targeted screening to aid early detection. Since the molecular events leading to CRC have become better characterized, there is also the possibility of developing chemoprotective agents.