Fecal occult blood screening for colorectal cancer.

Fecal occult blood testing with guaiac gum is a simple, safe, and cheap method for screening for colorectal cancer. In the office setting, compliance is good. Asymptomatic colorectal cancers are detected at a more favourable pathologic stage than those detected in symptomatic patients. Because of the low positive predictive value of the test, many persons testing positive undergo unnecessary bowel examinations. As yet, randomized controlled studies have not shown that fecal occult blood screening reduces mortality from colorectal cancer. At present, screening with this test is left to the judgement of the individual physician.