[Screening for colorectal cancer with an immunological fecal occult blood test]

Despite worldwide recommendations, the screening for colorectal cancer (CRC) is not routinely performed in our country. Consequently, we conducted a pilot study to evaluate an immunological fecal occult blood test (FOBT).

We studied 332 average-risk patients (age over 50 years, asymptomatic, with no personal or family history of CRC) who consulted primary care-generalists from Buenos Aires. They were randomly assigned to screening with one (group I) or three (group II) samples of FOBT (OC-Hemodia). Colonoscopy and/or barium enema and upper gastrointestinal endoscopy were indicated to patients with one or more positive samples.

141 of 162 patients in group I (87.0%) and 142 of 170 patients in group II (83.5%) returned samples (NS). Three of 162 patients were tested positive in group I (1.8%) and 15 of 170 in group II (8.8%) (P = 0.005), with a global positivity of 5.4%. The colon was examined in 14 patients (77.8%) and 4 did not attend after repeated calls. Colonic study showed: CRC 1, adenomatous polyps 3, adenomatous polyps and hemorrhoids 1, diverticula 5, hemorrhoids 1, normal 2, intolerance 1. Upper endoscopy was performed in 9 patients: erosive gastritis 4, duodenal ulcer 1, normal 4. Both studies were normal in only 1 patient.

1) Immunological FOBT had a good compliance and an adequate positivity rate to be used in the screening for CRC. 2) Despite the use of an immunological test three samples are required to improve results. 3) Upper and lower gastrointestinal lesions, including CRC and polyps, were detected in almost all patients who were examined. 4) Our data justify the use of FOBT in wider population studies to assess its efficacy in the prevention of CRC.