Mass screening for colorectal cancer by testing fecal occult blood.

The validity of screening for colorectal cancer by testing for occult blood on 2 successive days was evaluated over a 2-year period beginning April 1980 by testing 9449 individuals without symptoms. The Shionogi slide (Shionogi Pharmaceutical Co., Osaka, Japan), a commercial guaiac-impregnated slide with moderate sensitivity, was used for screening subjects under dietary restriction. Of the 1401 persons (14.8%) who had a positive reaction for occult blood, 858 (61.2%) received further diagnostic examinations, and 265 of them proved to have one or more abnormalities of the gastrointestinal tract. Colorectal cancer was detected in 11 persons and polyps in 91 persons. Eight of the cancers were in an early stage. This screening method was found to be suitable for large-scale mass screening, and appears to have high diagnostic value.