Detection of colorectal cancer in symptomatic outpatients without visible rectal bleeding: Validity of the fecal occult blood test

Abstract

Background: In 2002, a new diagnostic strategy in symptomatic outpatients without known established colorectal cancer risk factors aged 40 years or older was implemented in Denmark. Fecal occult blood test (Hemoccult Sensa®) was a part of that strategy in patients without visible rectal bleeding.

Aims: The aim was to assess the validity of the Hemoccult Sensa® test in detecting colorectal cancer in the above-mentioned outpatients.

Patients: Symptomatic outpatients without known established colorectal cancer risk factors and without visible rectal bleeding.

Methods: Hemoccult Sensa® was performed before endoscopic examination. Colorectal cancer was identified at histopathological examination. Patients completed a questionnaire about their symptoms before their first hospital appointment.

Results: Eight of 256 patients were found to have colorectal cancer. Median patient age was 63 years. The positive predictive value, negative predictive value, sensitivity, and specificity of Hemoccult Sensa® for colorectal cancer were 10.5% (95% confidence interval [CI]: 6.8-14.3), 99.0% (95% CI: 97.8-100.0), 75.0% (95% CI: 69.7-80.3), and 79.4% (95% CI: 74.5-84.4).

Conclusions: Hemoccult Sensa® as the initial examination in symptomatic outpatients without known established colorectal cancer risk factors presenting without rectal bleeding has to be used with caution. We did not find Hemoccult Sensa® test to be an acceptable alternative to flexible sigmoidoscopy.

Keywords: colorectal neoplasms; diagnostic tests; occult blood; sensitivity; specificity.