[Comparison of chemical and immunological methods in fecal occult blood testing]

Conventional occult blood testing using the chemical method has been compared with newly developed immunological testing methods; the Hemoccult slide II (HEM II) test has been widely accepted as a guaiac test but such recent tests as the Latex agglutination test (Latex) and the Enzyme Immunoassay method (EIA) have also come to be employed. Thirty colorectal cancer patients, 30 gastric cancer patients and 30 healthy persons were subjected the three above described tests during 3 consecutive days while under no restricted diet. False positive rates during this three-day testing period were 26.7% in HEM II, 93.3 in Late and 8.3% in EIA. Although the immunological testing method has the advantage of reducing the false positive rate without the need for a restricted diet it is time-consuming and expensive. Considering these results as well as our previous knowledge accrued from a mass survey, it is suggested that a new flow-chart may be found necessary, in which an initial screening is given by the chemical method and then followed by a secondary screening by the immunological method. This new flow-chart, if routinely employed, would greatly facilitate the mass screening of colorectal cancer.