Occult-blood screening for colorectal carcinoma: the benefits.

Preventive medical interventions directed at the general population require rigorous evaluation of the associated benefits, risks, and costs. This paper, the first of a three-part series, assesses the current evidence for the effectiveness of occult-blood (Hemoccult) screening for colorectal carcinoma. When judged by explicit methodologic criteria for the effectiveness of screening, that evidence demonstrates no clearcut benefits to patients found to have colorectal cancer through testing for occult blood. In contrast, there may be substantial risks and costs associated with the widespread use of this preventive maneuver. These are considered in two companion papers.