Fecal occult blood test screening for colorectal cancer.

In summary, high-quality scientific studies indicate that the use of the FOBT for colorectal cancer screening has a number of important advantages. The test is capable of detecting most early colorectal cancers and many advanced adenomas. It has been shown in randomized, controlled trials to reduce substantially colorectal cancer mortality and incidence. The FOBT is feasible, widely available, and acceptable to most individuals. It has a low up-front cost and is highly cost-effective. Combining annual FOBT with periodic flexible sigmoidoscopy seems to be an especially effective screening option. Limitations of FOBT screening include its low sensitivity for polyps, especially smaller ones. Some of the trials report a relatively low sensitivity for detecting cancers located in the distal colon. The test has a relatively low specificity, so there are many false-positive screens; and for it to be most effective, repetitive screening is necessary. Balancing these advantages and disadvantages, the evidence-based screening guidelines have concluded that FOBT screening has a major role to play in colorectal cancer control and a program of annual FOBT plus flexible sigmoidoscopy every 5 years is a preferred option for screening the asymptomatic, average-risk population for colorectal cancer. Short of doing direct colonoscopy screening for the entire at-risk population, the FOBT currently is the best available method of identifying asymptomatic, average-risk people most likely to benefit from colonoscopy.