[Evaluation of usefulness of faecal occult blood test. Prospective screening study in patients with colorectal neoplasia]

Abstract

High incidence of colorectal cancer (CRC), good treatment outcome in case of surgery performed at an early stage of the disease, and a simple, low cost and quick diagnostic test, encourage the common use of screening for CRC. The aim of the study was to examine the efficacy of immunochromatographic faecal occult blood (FOB) testing in screening for early colorectal cancer.

Material and methods: A total of 346 subjects with abdominal symptoms of unclear etiology were included to the study. Patients with diagnosed CRC, clinical symptoms suggesting CRC or those with family history of CRC were excluded from the study. All subjects had FOB testing done. All were subjected to sigmoidoscopy, no matter what the result of the screening test was. The sensitivity and specificity of the screening test for CRC was evaluated.

Results: The total of 342 subjects aged 29-68 years (median 59 yrs), including 189 (58%) females and 153 (42%) males, were eventually qualified for the study. Colorectal pathology was found in 117 subjects (34.6%). Out of 62 patients with positive tests, 55 (89%) had a colorectal disorder diagnosed during sigmoidoscopy. The results were false positive in 7 cases. Colorectal neoplasia was recognized in 33 cases. These were neoplastic polyps (23) and adenocarcinoma (10). The great majority of neoplastic conditions were found in FOB positive subjects. The sensitivity of the test was 90%, while its specificity reached 84%. Diagnostic accuracy was 84%. Positive and negative predictive values were 15% and 99% respectively.

Conclusions: FOB testing appears highly sensitive and specific for colorectal cancer in patients with unclear abdominal symptoms.