Update on colorectal cancer. Risk factors, diagnosis, and treatment.

Colorectal cancer is more common in the Western world than in underdeveloped countries. Diet, longevity, heredity, and presence of other bowel diseases may affect the incidence. Diagnosis is based on results of routine laboratory studies and evaluation of the entire large bowel with air-contrast barium enema and colonoscopy. Surgical resection is the primary therapy for colorectal cancer. Postoperative systemic chemotherapy yields poor results, but hepatic artery infusional chemotherapy offers some benefit to patients who have only hepatic metastases. Follow-up evaluation includes physical examination and laboratory studies every 3 months for the first 2 years and colonoscopy every year.