Occult Blood Screening for Colorectal Cancer

GENERAL BACKGROUND  Colorectal cancer has long been the target of efforts aimed at early detection. It is the second most common cancer in the United States, with 140 000 new cases and 60 000 deaths estimated to have occurred in 1987.¹ It is uncommon in persons younger than 50 years but its incidence increases sharply thereafter.² Investigations into the causes of colorectal cancer have not yielded a consensus strategy for prevention. However, early treatment generally is acknowledged to be more beneficial than late treatment. Early detection would thus seem to be a reasonable approach to lowering the toll of this cancer.The American Cancer Society and the National Cancer Institute recommend yearly occult blood testing for all persons older than 50 years of age.^3,4 The Canadian Task Force on the Periodic Health Examination has recommended the use of fecal occult blood testing by asymptomatic persons older than